Account Abstraction
A blockchain design where user accounts can have programmable validation logic, enabling features like social recovery and gas sponsorship.
Account Funding Transaction (AFT)
An account funding transaction uses a debit or credit card to load funds into a non-card account like a crypto exchange, wallet, or prepaid card.
Account Model
A blockchain state model that tracks balances per address like a bank account, used by Ethereum and Solana instead of Bitcoin's UTXO model.
Account Updater
Account updater is a card network service that automatically refreshes stored card credentials when a card is reissued, expired, or replaced.
Account-to-Account Payments (A2A)
Direct bank-to-bank transfers that bypass card networks, reducing costs for merchants and enabling instant settlement.
Accredited Investor
An accredited investor is an individual or entity meeting SEC wealth or income thresholds, qualifying them for unregistered securities offerings.
ACH Transfer
The Automated Clearing House network processes batch electronic payments in the US, handling payroll, bills, and bank transfers.
Acquirer (Acquiring Bank)
The bank or financial institution that processes card payments on behalf of a merchant, managing settlement and risk.
Acquiring Processor
A technology company that handles the technical transaction processing on behalf of acquiring banks, connecting merchants to card networks.
Actively Validated Service (AVS)
An AVS borrows economic security from a restaking layer like EigenLayer instead of bootstrapping its own validator set from scratch.
Adaptor Signature
A cryptographic primitive enabling conditional signatures that become valid only when a secret is revealed, powering trustless atomic protocols.
Address Clustering
A chain analysis technique that groups Bitcoin addresses likely controlled by the same entity using transaction pattern heuristics.
Address Encoding
How Bitcoin addresses are encoded using Base58Check, Bech32, and Bech32m to prevent errors and identify network types.
Address Gap Limit
The number of consecutive unused addresses a wallet scans before stopping, affecting fund discovery in HD wallets.
Address Poisoning
Address poisoning is a scam where attackers send tiny transactions from look-alike addresses to trick victims into copying the wrong one.
Address Reuse
Using the same Bitcoin address for multiple transactions, which degrades privacy by linking all activity to one identity.
Address Verification Service (AVS)
Address Verification Service (AVS) is a fraud prevention tool that checks billing address data against the card issuer's records.
Air-Gapped Signing
Signing Bitcoin transactions on a device permanently disconnected from any network, transferring data via QR codes or microSD cards.
Airdrop
Free distribution of tokens to wallet addresses, used for protocol launches, community rewards, and retroactive funding.
Algorithmic Stablecoin
A stablecoin that maintains its peg through automated supply adjustments rather than collateral reserves.
All-Time High (ATH)
The highest price ever reached by a cryptocurrency, a key psychological and technical level tracked by traders and investors.
Altcoin
An altcoin is any cryptocurrency other than Bitcoin, ranging from Ethereum and Solana to meme tokens and stablecoins.
AMP (Atomic Multi-Path Payment)
A spontaneous multi-path payment protocol using base preimages that doesn't require an invoice from the recipient.
Anchor Outputs
Special outputs in Lightning commitment transactions that enable dynamic fee bumping during force closes, solving fee volatility issues in channel disputes.
Anchoring Transaction
An anchoring transaction is an on-chain Bitcoin transaction that commits the state of an off-chain protocol to the base layer.
Anti-Replay Protection
Mechanisms that prevent valid transactions on one blockchain fork from being rebroadcast on another after a chain split.
App Chain (Application-Specific Blockchain)
An app chain is a blockchain built and optimized for a single application or use case rather than general-purpose computation.
APY vs APR
APY and APR are interest rate metrics used in DeFi and lending, differing in whether compounding is included in the calculation.
Arbitrage
Arbitrage is the practice of profiting from price differences for the same asset across different markets or exchanges.
Archive Node
An archive node stores the complete historical state of a blockchain at every block height, enabling full historical queries and analytics.
Ark Protocol
A Bitcoin Layer 2 design using virtual UTXOs (vTXOs) and a coordinator to enable off-chain transfers with non-interactive recipient experience.
ASIC Miner
An Application-Specific Integrated Circuit designed exclusively for Bitcoin mining, vastly outperforming general-purpose hardware.
Asset-Referenced Tokens (ARTs)
A MiCA-defined category of crypto-assets that maintain stable value by referencing multiple currencies, commodities, or other assets, subject to strict EU reserve and governance requirements.
AssumeUTXO
A Bitcoin Core optimization that lets nodes start with a pre-validated UTXO set snapshot, becoming usable in minutes instead of hours.
AssumeValid
A Bitcoin Core optimization that skips signature verification for blocks below a hardcoded checkpoint, dramatically speeding up initial sync.
Async Payments
Async payments are a Lightning Network extension allowing users to receive payments even when their node is temporarily offline.
Asynchronous Payment Channel
An asynchronous payment channel enables payments to offline recipients without requiring both parties to be online simultaneously.
Atomic Multi-Path (AMP)
A Lightning Network payment method that splits a single payment across multiple routes while ensuring atomic all-or-nothing delivery.
Atomic Multipath Payments (AMP)
A Lightning Network payment protocol that splits large payments across multiple paths using cryptographic secret sharing, ensuring all parts arrive or none do.
Atomic Settlement
A settlement mechanism where multiple legs of a transaction either all complete simultaneously or none do, eliminating counterparty risk.
Atomic Swap
A trustless exchange of cryptocurrencies between two parties where either both transfers complete or neither does.
Attestation
An attestation is a cryptographic statement or proof that verifies a claim about data, identity, or state without revealing underlying information.
Authorization and Capture
The two-step card payment process: first reserving funds (authorization), then collecting them (capture) when the order is fulfilled.
Authorized Participant (AP)
An authorized participant is a financial institution allowed to create and redeem ETF shares directly with the fund, keeping the market price aligned with NAV.
Auto-Compounding
Auto-compounding automatically reinvests earned yield back into the principal position, maximizing returns through compound interest without manual action.
Autoloop
An automated liquidity management system that uses rules-based submarine swaps to maintain optimal channel balances on Lightning Network nodes.
Automated Clearing House (ACH)
The Automated Clearing House is a US electronic payment network that processes batch transactions between banks for deposits and bill payments.
Automated Market Maker (AMM)
A smart contract that provides liquidity for token swaps using mathematical formulas instead of traditional order books.
Babylon Protocol
A Bitcoin staking protocol that enables BTC holders to provide economic security to proof-of-stake networks without bridging or wrapping.
Backrunning
An MEV strategy where a searcher places a transaction immediately after a target transaction to profit from the resulting state change.
Backwardation
Backwardation occurs when futures prices trade below the spot price, typically signaling strong immediate demand or bearish sentiment in crypto markets.
BACS Payments
The UK's bulk payment system processing direct debits and credits with a 3-day clearing cycle for payroll and recurring payments.
Bandwidth Attack
A bandwidth attack overwhelms a Bitcoin node's network connection by flooding it with excessive data, degrading its ability to relay transactions.
Bandwidth-Based Fee
A transaction fee model that charges based on the data size or bandwidth consumed rather than a flat rate per operation.
Bank Secrecy Act (BSA)
The Bank Secrecy Act is the foundational U.S. anti-money laundering law requiring financial institutions to report suspicious transactions.
Banking-as-a-Service (BaaS)
API-driven platforms that let non-bank companies embed banking features like accounts, cards, and payments into their products.
Base Fee (Lightning)
The base fee is a fixed satoshi amount charged by a Lightning routing node for forwarding a payment, regardless of the payment size.
Base Layer (Layer 1)
The base layer is the foundational blockchain that provides final settlement and security, upon which Layer 2 protocols are built.
Based Rollup
A based rollup delegates transaction sequencing to the base layer's validators rather than using a centralized sequencer.
Basis Trade
A basis trade exploits the price difference between a spot asset and its futures contract, earning the spread as the futures converge to spot at expiry.
Batch Processing (Payments)
Grouping multiple payment transactions together for processing at scheduled intervals rather than individually in real-time.
Batch Verification
Batch verification checks multiple Schnorr signatures simultaneously, validating a block of transactions faster than checking each one alone.
Bear Market
A prolonged period of declining cryptocurrency prices, typically defined as a 20% or greater drop from recent highs.
Bearer Asset
A bearer asset is property where possession alone proves ownership, with no registry or identity verification required to transfer or redeem it.
Bech32 and Bech32m
Human-readable address encoding formats for SegWit and Taproot Bitcoin addresses, with error detection and no mixed-case confusion.
Beneficial Ownership
The identification of the natural persons who ultimately own or control a legal entity, required by anti-money laundering regulations.
BGP Hijacking
An internet routing attack that can intercept Bitcoin network traffic by falsely advertising ownership of IP address ranges.
Bid-Ask Spread
The bid-ask spread is the difference between the highest price a buyer will pay and the lowest price a seller will accept for an asset, serving as a key measure of market liquidity.
BIN (Bank Identification Number)
The first 6-8 digits of a payment card number that identify the issuing bank, card brand, and card type.
BIP-174 (PSBT Format)
The specification for Partially Signed Bitcoin Transactions, enabling offline signing and multi-party transaction construction.
BIP-32 (HD Wallets)
The Bitcoin Improvement Proposal defining hierarchical deterministic key derivation from a single master seed.
BIP-324 (Encrypted P2P Transport)
BIP-324 adds opportunistic encryption to Bitcoin's peer-to-peer protocol, preventing passive eavesdropping on node traffic.
BIP-327 (MuSig2)
The specification for MuSig2, a two-round Schnorr multisignature protocol that produces a single aggregated signature indistinguishable from a regular single-signer signature on-chain.
BIP-340 (Schnorr Signatures for Bitcoin)
The specification defining how Schnorr signatures work in Bitcoin, using the secp256k1 curve with x-only public keys.
BIP-341 (Taproot Spending Rules)
The specification defining Taproot's output structure, key-path spending, and script-path spending via Merkle branches.
BIP-342 (Tapscript)
The specification defining the updated script validation rules for Taproot's script-path spending, with improved opcodes.
BIP-350
BIP-350 defines the Bech32m address encoding format used for SegWit version 1 and later Bitcoin addresses including Taproot.
BIP-353 (DNS Payment Instructions)
A Bitcoin standard enabling human-readable payment instructions via DNS, mapping names like user@domain to payment details such as BOLT-12 offers and on-chain addresses.
BIP-360 (Pay-to-Quantum-Resistant-Hash)
A Bitcoin Improvement Proposal introducing a quantum-resistant address format to protect funds against future quantum computing attacks.
BIP-39 (Mnemonic Seed Phrases)
The standard defining how mnemonic word lists encode wallet seeds, enabling human-readable backup of Bitcoin keys.
BIP-44 (Multi-Account Hierarchy)
A standard derivation path structure for HD wallets, organizing keys by purpose, coin type, and account for interoperable wallet recovery.
BIP-47 (Reusable Payment Codes)
A protocol enabling reusable Bitcoin addresses through payment codes, improving privacy while maintaining a static identifier.
BIP-84 (Native SegWit Derivation)
The standard derivation path for native SegWit (bech32) addresses, using m/84'/0'/0' for the most fee-efficient Bitcoin address format.
BIP-86 (Taproot Derivation)
The standard derivation path for Taproot (P2TR) addresses, using m/86'/0'/0' for key-path-only spending.
Bitcoin Address Types
The different address formats used in Bitcoin, from legacy (1...) to SegWit (bc1q...) to Taproot (bc1p...), each with different features and fee costs.
Bitcoin Core
The reference implementation of the Bitcoin protocol, maintained by hundreds of contributors and running on the majority of full nodes.
Bitcoin Dominance
Bitcoin dominance is the percentage of total cryptocurrency market capitalization that Bitcoin represents, used as a market sentiment indicator.
Bitcoin ETF (Exchange-Traded Fund)
A Bitcoin ETF is a regulated investment fund traded on stock exchanges that gives investors exposure to Bitcoin without holding it directly.
Bitcoin Full Node
Software that validates every Bitcoin transaction and block against consensus rules, without trusting any third party.
Bitcoin Halving
The programmatic event every 210,000 blocks (~4 years) that cuts the mining reward in half, enforcing Bitcoin's fixed supply schedule.
Bitcoin Improvement Proposal (BIP)
The formal process for proposing and documenting changes to the Bitcoin protocol, similar to Python's PEPs or Ethereum's EIPs.
Bitcoin L2 Landscape
The ecosystem of Layer 2 protocols building on Bitcoin, from Lightning to sidechains to rollups, each with different trust and scaling tradeoffs.
Bitcoin Maximalism
A philosophical position holding that Bitcoin is the only cryptocurrency with lasting value due to its decentralization and fixed supply.
Bitcoin Optech
A nonprofit providing technical resources, newsletters, and compatibility guides to help Bitcoin companies adopt scaling technologies.
Bitcoin Regtest
A local Bitcoin regression testing network where developers can instantly generate blocks on demand for automated testing.
Bitcoin Relay Network
Specialized networks that optimize block and transaction propagation between miners and nodes for faster distribution across the Bitcoin network.
Bitcoin RPC Interface
The JSON-RPC API that Bitcoin Core exposes for programmatic interaction, enabling wallet operations, node management, and blockchain queries.
Bitcoin Script
A stack-based programming language used to define spending conditions for Bitcoin outputs.
Bitcoin Script Limitations
The intentional constraints on Bitcoin's scripting language that prevent loops, limit stack size, and restrict computation for security.
Bitcoin Signet
A test Bitcoin network where blocks require a valid signature, providing a more predictable testing environment than testnet.
Bitcoin Staking
Protocols that enable Bitcoin holders to stake BTC to secure proof-of-stake networks and earn yield without wrapping or bridging.
Bitcoin Testnet
A separate Bitcoin network using worthless coins for developers to test applications and protocol changes without risking real funds.
Bitcoin Transaction Lifecycle
The complete journey of a Bitcoin transaction from creation through signing, broadcast, mempool, confirmation, and finality.
BitVM
A computing paradigm enabling arbitrary computation verification on Bitcoin through optimistic fraud proofs, without consensus changes.
Blended Pricing
Blended pricing is a merchant payment processing model that charges a single flat rate per transaction regardless of card type, brand, or interchange category.
Blind Merge Mining (BMM)
Blind merge mining allows Bitcoin miners to validate sidechain blocks without running sidechain software, using only Bitcoin transactions.
Blind Signature
A blind signature lets a signer sign a message without seeing its content, enabling private digital cash systems like Chaumian ecash.
Blinded Paths
A privacy feature that hides the final destination of a payment by providing an encrypted route from an introduction point.
Blob Transaction (EIP-4844)
A blob transaction carries large data blobs used by rollups for cheaper data availability on Ethereum's Layer 1.
Block Builder
A specialized entity that constructs optimized block contents by ordering transactions to maximize extracted value and fees.
Block Confirmation
A block confirmation occurs each time a new block is added on top of the block containing a transaction, increasing settlement certainty.
Block Explorer API
A block explorer API provides programmatic access to blockchain data including transactions, addresses, blocks, and mempool state.
Block Header
The 80-byte metadata structure at the start of each Bitcoin block containing the version, previous hash, Merkle root, timestamp, target, and nonce.
Block Height
Block height is the sequential number assigned to each block in a blockchain, counting from the genesis block at height zero.
Block Propagation
The process of distributing newly mined blocks across the Bitcoin network, where speed is critical for mining fairness.
Block Reward
The block reward is the total compensation a Bitcoin miner receives for adding a new block, combining the subsidy and transaction fees.
Block Size Limit
The maximum size of a Bitcoin block, currently measured in weight units (4M WU) after SegWit, constraining transaction throughput.
Block Space
Block space is the limited storage capacity within each Bitcoin block, functioning as a scarce resource that transactions compete for through fee-based bidding.
Block Subsidy
The newly minted Bitcoin awarded to miners for successfully mining a block, halving approximately every four years.
Block Template
The candidate block structure containing selected transactions that a miner attempts to find a valid hash for.
Block Time
The average interval between Bitcoin blocks, targeted at 10 minutes by the difficulty adjustment algorithm.
Block Withholding Attack
A mining pool attack where a malicious participant submits partial proofs of work but withholds valid blocks to harm the pool.
Blockchain
A blockchain is a distributed, append-only ledger that records transactions in linked blocks secured by cryptographic hashes.
Blockchain Explorer
A blockchain explorer is a web tool for searching and viewing transactions, addresses, blocks, and other on-chain data in real time.
Blockchain Indexer
A blockchain indexer processes and organizes raw blockchain data into queryable databases for fast lookups by apps and explorers.
Blockchain Oracle
A service that feeds external data (prices, events, randomness) to smart contracts that can't access off-chain information directly.
Blockchain Pruning
Discarding historical block data after validation to save disk space while maintaining full consensus verification capabilities.
Blockchain Trilemma
The blockchain trilemma states that a blockchain can optimize for only two of three properties: decentralization, security, and scalability.
Bloom Filter
A bloom filter is a probabilistic data structure used in Bitcoin SPV clients to request relevant transactions without revealing addresses.
BOLT (Basis of Lightning Technology)
BOLTs are the formal specification documents that define the Lightning Network protocol, covering channels, routing, and payment encoding.
BOLT Specifications
The Basis of Lightning Technology documents that define the Lightning Network protocol standards.
BOLT-11 Invoice Format
The original Lightning payment request format encoding amount, destination, payment hash, and routing hints in a bech32 string.
BOLT-12 Offers
A new Lightning invoice format that enables reusable payment requests, subscriptions, and enhanced privacy through blinded paths.
Bonding Curve
A bonding curve is a mathematical formula that automatically sets a token's price based on its supply, used in DeFi token issuance.
Bootstrap Node
A hardcoded network node that new Bitcoin clients connect to first in order to discover other peers on the network.
Brain Wallet
A brain wallet derives a Bitcoin private key from a memorized passphrase, offering portability but critically weak security against brute-force attacks.
BRC-20
An experimental fungible token standard on Bitcoin using Ordinals inscriptions to track token deployments, mints, and transfers.
Breez SDK
A development kit for building Lightning-enabled applications, abstracting channel management and liquidity complexity.
Bridge Aggregator
A bridge aggregator compares routes across multiple cross-chain bridges to find the cheapest and fastest path for transferring assets between blockchains.
Bridge Security Models
The spectrum of trust assumptions in cross-chain bridges, from centralized custodians to trustless light client verification.
Broadcast Transaction
Broadcasting a transaction means sending a signed Bitcoin transaction to the peer-to-peer network so miners can include it in a block.
BTCFi (Bitcoin Finance)
The ecosystem of DeFi protocols and financial services built on Bitcoin and its Layer 2 networks for lending, staking, and yield.
Bull Market
A sustained period of rising cryptocurrency prices driven by optimism, adoption momentum, and increased buying activity.
Bulletproofs
A zero-knowledge proof system for range proofs that requires no trusted setup, used for confidential transaction amounts.
Burn Address
A cryptocurrency address with no known private key, used to permanently remove tokens from circulation.
Buy Now, Pay Later (BNPL)
A point-of-sale financing option that splits purchases into interest-free installments, offered by providers like Klarna and Affirm.
Byzantine Fault Tolerance (BFT)
Byzantine fault tolerance is a system's ability to function correctly even when some nodes act maliciously or send conflicting information.
Calldata
The read-only data payload attached to an Ethereum transaction, commonly used by rollups for data availability on Layer 1.
Canary Transaction
A watchdog transaction designed to alert its creator if a particular signing key or wallet has been compromised.
Cantillon Effect
The uneven distribution of new money's impact, where those closest to the money source benefit most before prices rise broadly.
Capacity Planning (Lightning)
Lightning capacity planning involves strategically allocating funds across channels to maximize routing success and fee revenue.
Capital Efficiency
Capital efficiency measures how effectively deposited assets generate returns or utility relative to the amount locked.
Card Network
Companies like Visa and Mastercard that set rules, route transactions, and provide infrastructure connecting card issuers and acquirers.
Card on File (CoF)
Card on file refers to a stored payment credential that a merchant retains to process future transactions without re-entering card details.
Card-Not-Present Payment (CNP)
An online or phone transaction where the physical card is absent, carrying higher fraud risk and interchange rates.
Card-Present Payment
An in-person transaction where the physical card or device is used at a terminal, offering lower fraud risk and interchange rates.
CBDC (Central Bank Digital Currency)
A digital form of a country's fiat currency issued directly by the central bank, aiming to modernize money and payments.
Censorship Resistance
Censorship resistance is a blockchain property ensuring no single entity can prevent valid transactions from being confirmed.
Central Bank Money
Central bank money is currency issued directly by a central bank, including physical cash and reserves held by commercial banks.
Chain Abstraction
Chain abstraction hides multi-chain complexity from users, letting them interact with any blockchain without manually bridging or switching networks.
Chain Analysis (Blockchain Analytics)
The practice of analyzing blockchain transactions to identify, cluster, and trace activity for compliance, law enforcement, or intelligence.
Chain ID
A chain ID is a unique numerical identifier assigned to a blockchain network to prevent transaction replay across different chains.
Chain Reorganization (Reorg)
When a Bitcoin node switches to a longer valid chain, potentially reverting previously confirmed transactions.
Chain State (UTXO Set Database)
The current set of all unspent transaction outputs that a Bitcoin node maintains to validate new transactions.
Chain Tip
The chain tip is the most recently validated block in a node's view of the blockchain, representing the current state of the ledger.
Change Output
The UTXO returned to the sender when a Bitcoin transaction spends more than the payment amount, like getting change from cash.
Channel Balance
Channel balance is the distribution of funds between two Lightning channel participants, determining how much each side can send or receive.
Channel Capacity
The total amount of Bitcoin locked in a Lightning channel, representing the maximum that can be transferred in either direction.
Channel Factory
A proposed multi-party channel setup that enables efficient batch opening and closing of Lightning payment channels, significantly reducing on-chain footprint and improving scalability.
Channel Jamming
An attack that locks up Lightning channel liquidity by sending payments that are held indefinitely, degrading routing.
Channel Reserve
The minimum balance that must be maintained in a Lightning Network channel to ensure both parties can cover potential closure fees and prevent gaming the system.
Channel Reserve
A minimum balance each party must maintain in a Lightning channel, ensuring they have something to lose if they cheat.
Chantools
A command-line toolkit for Lightning Network channel recovery and troubleshooting, used to rescue funds from stuck, force-closed, or corrupted channels.
CHAPS Payments
The UK's real-time gross settlement system for high-value sterling payments, operated by the Bank of England.
Chargeback
A forced transaction reversal initiated by a cardholder's bank, designed to protect consumers but costing merchants billions annually.
Chaumian E-Cash
Chaumian e-cash is a digital cash system using blind signatures to enable private, untraceable payments through a centralized mint.
Checksum
A short value derived from a data block used to detect errors in Bitcoin addresses, keys, and network messages.
Child-Pays-for-Parent (CPFP)
A fee-bumping technique where spending an unconfirmed output with a high-fee transaction incentivizes miners to include both.
CHIPS (Clearing House Interbank Payments System)
The Clearing House Interbank Payments System processes large-value US dollar payments between banks, settling $1.8 trillion daily.
Circuit Breaker (Lightning)
A Lightning node tool that rate-limits HTLC forwarding to protect against channel jamming and routing abuse.
Circular Rebalance
A Lightning Network liquidity management technique where node operators send payments to themselves through external routes to shift channel balances.
Circulating Supply
Circulating supply is the number of cryptocurrency tokens currently available for trading, excluding locked, vested, or burned tokens.
Clearing
The process of reconciling and netting payment obligations between banks before final settlement of funds.
Click to Pay
A unified online checkout standard backed by major card networks that replaces manual card entry with tokenized one-click payments.
Clipboard Hijacking
Malware that monitors the clipboard and replaces copied Bitcoin addresses with attacker-controlled addresses to redirect payments.
Closed-Loop Payment System
A payment network where the same entity controls issuance, processing, and settlement, like a gift card or proprietary wallet.
CLTV Expiry Delta
The number of blocks a Lightning routing node requires between incoming and outgoing HTLC timelocks to safely claim payments.
Cluster Mempool
Cluster mempool is a redesigned Bitcoin Core memory pool that groups related transactions for more optimal fee-based ordering.
Coin Age
A metric that multiplies the number of coins by the time they have been held, used in on-chain analysis and some consensus designs.
Coin Control
Manually selecting which UTXOs to spend in a transaction, giving users control over privacy and fee optimization.
Coin Days Destroyed (CDD)
Coin days destroyed measures Bitcoin economic activity by weighting transactions by how long the coins were held before moving.
Coin Hours
Coin hours measure the cumulative age of unspent Bitcoin, calculated as the number of coins multiplied by the time they have remained unspent.
Coin Selection Algorithm
The algorithm a wallet uses to choose which UTXOs to spend, optimizing for fees, privacy, and UTXO set management.
Coinbase Field (Arbitrary Data)
The input data field in a coinbase transaction that miners can fill with arbitrary content, used for block height, pool identification, and messages.
Coinbase Maturity
The 100-block waiting period before newly mined Bitcoin can be spent, protecting against chain reorganization losses.
Coinbase Transaction
The first transaction in every Bitcoin block that creates new coins as the mining reward and collects transaction fees.
CoinJoin
A Bitcoin privacy technique where multiple users combine their transactions into one, making it difficult to trace which inputs paid which outputs.
CoinSwap
A privacy protocol where two parties exchange Bitcoin outputs without a visible on-chain link, making transaction tracing much harder.
Cold Storage
Storing cryptocurrency private keys on devices that are never connected to the internet, maximizing security against remote attacks.
Collateral Factor
The collateral factor is the percentage of a deposited asset's value that can be borrowed against in a DeFi lending protocol, reflecting the asset's risk profile.
Commingling
The prohibited practice of mixing customer funds with a company's own assets, a key concern in crypto custody and stablecoin reserves.
Commitment Scheme
A commitment scheme is a cryptographic protocol that lets you lock in a value (commit) and reveal it later without being able to change it.
Commitment Transaction
A pre-signed Bitcoin transaction representing the current balance of a Lightning channel, held by each party as insurance.
Commodity-Linked Synthetics
Digital assets that track the price of physical commodities like gold, silver, or oil through derivative mechanisms rather than direct physical backing.
Common-Input-Ownership Heuristic
The chain analysis assumption that all inputs in a Bitcoin transaction belong to the same entity, the most powerful tracing tool.
Compact Block Filters (Neutrino)
A privacy-preserving light client protocol where nodes download compact filters to find relevant blocks without revealing addresses.
Compact Blocks
A Bitcoin protocol optimization that reduces block propagation bandwidth by transmitting only short transaction IDs instead of full transactions.
Compact Fraud Proof
A succinct cryptographic proof demonstrating that a block or state transition is invalid, used in optimistic rollups and light clients.
Concentrated Liquidity
Concentrated liquidity lets DEX liquidity providers allocate capital within a specific price range, improving capital efficiency over full-range positions.
Concentrated Liquidity Market Maker (CLMM)
An AMM design where liquidity providers can allocate capital within specific price ranges for higher capital efficiency.
Confidential Transaction
A confidential transaction hides the payment amount using cryptographic commitments while still allowing validators to verify no coins were created.
Confirmation Bias (Trading)
A cognitive bias where crypto traders seek information that confirms their existing beliefs while ignoring contradictory evidence.
Confirmation of Payee (CoP)
Confirmation of Payee is a name-checking service that verifies a recipient's identity before a bank transfer is sent.
Connector Output
A special Bitcoin transaction output used in the Ark protocol to atomically link on-chain and off-chain state transitions, preventing double-spending without Lightning-style penalties.
Consensus Client
Software responsible for validating blocks and maintaining agreement on the canonical chain, distinct from the execution layer client.
Consensus Mechanism
A consensus mechanism is the protocol by which distributed nodes in a blockchain network agree on the current state of the ledger.
Contactless Payment (NFC)
A tap-to-pay transaction using NFC technology in cards or phones, enabling fast in-person payments without inserting cards.
Contango
Contango is a market condition where futures prices trade above the current spot price, reflecting costs of carry or bullish expectations.
Contract ABI (Application Binary Interface)
A contract ABI defines how to encode function calls and decode return values when interacting with an Ethereum smart contract.
Cooperative Close
A cooperative close is a mutually agreed channel closure in Lightning where both parties sign a final settlement transaction on-chain.
Cooperative Custody
A custody model where user and service provider jointly control keys, combining self-custody security with professional recovery support.
Copy Trading
Copy trading automatically replicates the positions and trades of experienced traders into a follower's account, proportional to their allocated capital.
Core Banking System
The central software platform that processes a bank's transactions, maintains accounts, and handles the ledger of record.
Core Lightning (CLN)
A modular Lightning implementation maintained by Blockstream, written in C with a plugin architecture for extensibility.
Correspondent Banking
A network of banking relationships enabling cross-border payments by routing funds through intermediary banks.
Cost Basis
Cost basis is the original purchase price of a cryptocurrency asset, used to calculate capital gains or losses when the asset is sold or traded.
Counterparty Risk
The risk that the other party in a financial transaction will fail to fulfill their obligations, a key concern in custodial crypto services.
Covenant
A proposed Bitcoin feature that would allow outputs to restrict how they can be spent in future transactions.
CPFP Carve-Out
CPFP carve-out is a Bitcoin mempool policy exception allowing a second-party child transaction to fee-bump even when mempool limits are reached.
Creation/Redemption Mechanism
The creation/redemption mechanism allows authorized participants to exchange ETF shares for the underlying assets, maintaining price-NAV alignment.
Cross Margin
Cross margin shares the entire account balance across all open positions to prevent liquidation, unlike isolated margin which limits risk per trade.
Cross-Border Acquiring
Processing card payments for merchants in a different country than the acquirer, enabling global commerce with complex fee implications.
Cross-Border Payments
Financial transactions where the payer and recipient are in different countries, involving currency conversion and multiple intermediaries.
Cross-Chain Atomic Swap
A cross-chain atomic swap enables trustless exchange of cryptocurrencies across different blockchains using hash time-locked contracts.
Cross-Chain Bridge
A protocol enabling asset or data transfer between different blockchains, with varying trust assumptions.
Cross-Chain Messaging
Protocols that transmit arbitrary data and instructions between blockchains, enabling cross-chain smart contract execution.
Cross-Currency Settlement
Cross-currency settlement is the process of completing a financial transaction where the payer and payee use different currencies.
Cross-Input Signature Aggregation (CISA)
A proposed Bitcoin upgrade allowing multiple transaction inputs to share a single aggregated Schnorr signature, reducing fees.
crvUSD Stablecoin
Curve Finance's stablecoin using a novel soft-liquidation mechanism called LLAMMA that gradually converts collateral instead of hard liquidations.
Crypto Compliance
Crypto compliance encompasses the regulatory requirements that crypto businesses must follow, including KYC, AML, sanctions screening, and licensing.
Crypto Custody
Crypto custody refers to the safekeeping of private keys and digital assets, ranging from self-custody wallets to institutional-grade solutions.
Crypto Derivatives
Crypto derivatives are financial contracts whose value is derived from an underlying cryptocurrency, including futures, options, and perpetual swaps.
Crypto Exchange
A crypto exchange is a platform where users can buy, sell, and trade cryptocurrencies using fiat currencies or other digital assets.
Crypto Lending
Crypto lending allows holders to earn interest by lending digital assets to borrowers through centralized platforms or decentralized protocols.
Crypto Prime Brokerage
A crypto prime broker provides institutional clients with bundled services including custody, lending, execution, and margin financing across multiple venues.
Crypto Tax
Crypto tax refers to the tax obligations triggered by selling, trading, or earning cryptocurrency, treated as property in most jurisdictions.
Crypto Winter
A crypto winter is a prolonged bear market in cryptocurrency, characterized by steep price declines, low trading volume, and industry contraction.
Cryptocurrency
Cryptocurrency is a digital asset that uses cryptographic techniques and blockchain technology to enable peer-to-peer transactions without relying on a central authority.
Cryptographic Agility
The ability of a system to switch between cryptographic algorithms without major redesign, critical for quantum migration readiness.
CTR (Currency Transaction Report)
A mandatory FinCEN filing for cash transactions exceeding $10,000 to detect potential money laundering through large currency movements.
CTV (CheckTemplateVerify)
CheckTemplateVerify (BIP 119) is a proposed Bitcoin opcode enabling basic covenants by committing to a specific future transaction template.
Custodial Lightning
Lightning Network wallets and services where a third party holds the user's private keys and manages channel liquidity.
Custodial Risk
Custodial risk is the danger of losing funds when a third party holding your cryptocurrency becomes insolvent, hacked, or dishonest.
DAI Stablecoin
A decentralized stablecoin generated by locking collateral in MakerDAO smart contracts, maintaining a soft dollar peg through overcollateralization and algorithmic stability mechanisms.
Dandelion Protocol
A P2P relay protocol that obscures the originating IP address of a Bitcoin transaction using stem-and-fluff propagation.
DAO (Decentralized Autonomous Organization)
An organization governed by smart contracts and token holder votes rather than traditional corporate hierarchy.
Dark Forest (Mempool)
The dark forest is a metaphor for the hostile blockchain mempool environment where predatory bots extract value from pending transactions.
Dark Pool (Crypto)
A crypto dark pool is a private trading venue where large orders are matched without displaying them publicly, reducing price impact and front-running.
Data Anchoring
The practice of embedding a hash or proof of external data into a blockchain transaction to create a timestamped, immutable record.
Data Availability
The guarantee that transaction data is published and accessible so anyone can verify state transitions and detect fraud.
Data Availability Sampling (DAS)
Data availability sampling lets light nodes verify that block data was published without downloading the full block, using random sampling and erasure coding.
De-Risking
The practice of financial institutions terminating or restricting relationships with entire categories of clients deemed high-risk, rather than managing risk on a case-by-case basis.
Dead Man's Switch
A mechanism that automatically transfers cryptocurrency to designated heirs if the owner fails to check in within a set time period.
Death Spiral
A self-reinforcing collapse mechanism in algorithmic stablecoins where falling prices trigger panic redemptions, further crashing the price until the peg breaks irreversibly.
Decentralized Application (dApp)
A decentralized application is software that runs on a peer-to-peer blockchain network rather than on centralized servers.
Decentralized Exchange (DEX)
A non-custodial trading platform where users swap tokens directly from their wallets without depositing funds to a central party.
Decentralized Finance (DeFi)
Decentralized finance (DeFi) is an ecosystem of financial applications built on blockchain that operates without traditional intermediaries.
Decentralized Identity (DID)
Decentralized identity is a self-sovereign framework where individuals control their own digital identity without relying on centralized authorities.
Decentralized Oracle Network
A network of independent nodes that aggregate off-chain data and deliver it to smart contracts with cryptographic guarantees.
Decline Code
A decline code is a numeric response from a card issuer or payment processor explaining why a transaction was rejected.
Deferred Net Settlement (DNS)
Deferred net settlement batches and offsets transactions over a period before settling only the net amounts between participants.
DeFi Composability
The ability to combine multiple DeFi protocols into complex financial workflows, often called money legos.
DeFi Protocol Risk
The various risks of using DeFi protocols including smart contract bugs, oracle failures, governance attacks, and economic exploits.
DeFi Vault
A smart contract that automates a specific yield strategy, allowing users to deposit and earn without active management.
Deflationary Token
A deflationary token is a cryptocurrency designed to decrease in supply over time through burn mechanisms or fee destruction.
Delegated Proof of Stake (DPoS)
A consensus mechanism where token holders vote for a small set of delegates who validate blocks on their behalf.
Delegated Staking
Delegated staking lets token holders assign their staking power to a validator without transferring custody, earning a share of staking rewards.
Delivery Versus Payment (DvP)
Delivery versus payment is a settlement mechanism ensuring that asset transfer and payment happen simultaneously, eliminating settlement risk.
Delta-Neutral Stablecoin
A delta-neutral stablecoin maintains its peg by holding a long crypto position hedged with a matching short derivative to eliminate price risk.
Deniability
Deniability in cryptocurrency refers to the ability to plausibly deny ownership of funds or participation in a specific transaction.
Depeg Event
When a stablecoin's market price diverges significantly from its target peg, often triggering panic and further instability.
Deposit Address
A deposit address is a unique blockchain address generated by an exchange or service where users send cryptocurrency to fund their account.
Derivation Path
A hierarchical path specifying how to derive a specific key from a master seed in an HD wallet.
Descriptor Wallet
A descriptor wallet uses output descriptors to precisely define which Bitcoin scripts and derivation paths a wallet can spend, replacing legacy key imports.
Deterministic Build
A deterministic build produces identical binary output from the same source code on any machine, enabling independent verification of software.
Deterministic Nonce (RFC 6979)
A deterministic nonce is generated from the private key and message using HMAC-DRBG, eliminating the risk of RNG failures during signing.
DEX Aggregator
A DEX aggregator routes trades across multiple decentralized exchanges to find the best price and lowest slippage for users.
Difficulty Adjustment
Bitcoin's automatic mechanism to maintain approximately 10-minute block intervals by adjusting the mining difficulty every 2016 blocks.
Difficulty Bomb
A mechanism in Ethereum that progressively increased mining difficulty to force the transition from proof-of-work to proof-of-stake.
Difficulty Epoch
The 2,016-block period between Bitcoin difficulty adjustments, approximately two weeks, during which the difficulty target remains constant.
Difficulty Ribbon
The Difficulty Ribbon plots multiple moving averages of Bitcoin's mining difficulty to visualize miner stress and identify optimal long-term accumulation periods.
Difficulty Target
The difficulty target is a 256-bit number that a Bitcoin block hash must be less than for the block to be accepted by the network.
Digital Asset
A digital asset is any digitally stored item of value, including cryptocurrencies, tokens, NFTs, and tokenized securities.
Digital Bearer Instrument
A digital bearer instrument is an electronic asset where possession of the cryptographic key equals ownership, with no registry needed.
Digital Signature
A digital signature is a cryptographic proof that the owner of a private key authorized a specific transaction or message.
Digital Wallet Pass
A virtual card or credential stored in mobile wallet apps like Apple Wallet or Google Wallet for contactless payments and identity verification.
Direct Debit
A recurring pull payment arrangement where a business is authorized to collect payments directly from a customer's bank account.
Disbursement
The outward payment of funds from a business to individuals, including payroll, refunds, insurance payouts, and vendor payments.
Discreet Log Contract (DLC)
A Bitcoin smart contract that uses oracle signatures to settle bets and financial derivatives without revealing contract details on-chain.
Dispute Resolution (Payments)
The formal process for handling transaction disagreements between cardholders, merchants, and banks under card network rules.
Distributed Key Generation (DKG)
Distributed key generation creates a shared cryptographic key across multiple parties so that no single party ever possesses the complete key.
DNS Seed
A DNS seed is a domain name that returns IP addresses of active Bitcoin nodes, helping new nodes discover peers when first joining the network.
Dollar Peg
A dollar peg is a mechanism that maintains a stablecoin's value at or near one US dollar through reserves, algorithms, or arbitrage.
Dollar Stablecoin
A cryptocurrency pegged 1:1 to the US dollar, backed by reserves of cash, treasuries, or equivalent liquid assets.
Dollar-Cost Averaging (DCA)
Dollar-cost averaging is an investment strategy of buying a fixed dollar amount of an asset at regular intervals regardless of price.
Dollar-Denominated Savings
Using dollar-pegged stablecoins as a savings vehicle in countries with high inflation or limited banking access.
Double Spend
An attack where the same Bitcoin is spent in two conflicting transactions, attempting to defraud a recipient.
Dual-Funded Channel
A Lightning channel where both parties contribute funds to the opening transaction, providing immediate bidirectional capacity.
Dunning
The automated process of retrying failed recurring payments and communicating with customers to recover revenue from payment failures.
Duress Wallet
A hidden secondary wallet activated by an alternative passphrase, designed to protect primary funds when the owner is under coercion.
Dust Attack
Sending tiny amounts of Bitcoin to many addresses to track spending patterns and deanonymize users when dust is consolidated.
Dust Consolidation
The process of combining many small-value UTXOs into fewer larger ones during low-fee periods to reduce future transaction costs.
Dust Limit
The minimum UTXO value that Bitcoin Core will create or relay, below which the output costs more in fees to spend than it's worth.
Dust Limit
The dust limit is the minimum UTXO value in Bitcoin below which a transaction output is rejected by nodes because it costs more to spend than it is worth.
Dusting Analysis
Dusting analysis is a blockchain surveillance technique that sends tiny amounts to addresses to track spending patterns and link identities.
Dutch Auction
A Dutch auction starts at a high price and gradually decreases until buyers accept the current price, used in token sales and NFT mints.
Dynamic Currency Conversion (DCC)
Dynamic currency conversion lets international cardholders pay in their home currency at point of sale, with the acquirer setting the exchange rate.
E-Money Directive (EMD2)
The E-Money Directive is EU legislation that regulates electronic money institutions and the issuance of digital stored value for payments.
E-Money License (EMI)
A European license authorizing companies to issue electronic money and provide payment services across the EU.
E-Money Tokens (EMTs)
A type of stablecoin under MiCA regulation that is pegged to a single fiat currency and backed by reserves, functioning as a digital representation of electronic money.
eCash (Chaumian eCash)
A digital cash system using blind signatures to enable private, untraceable payments through a mint, pioneered by David Chaum.
Eclair
A Scala-based Lightning implementation by ACINQ, powering the Phoenix mobile wallet and enterprise Lightning deployments.
Eclipse Attack
An attack isolating a node by controlling all its peer connections, enabling double spends or selfish mining against that node.
Economic Density
Economic density measures the total economic value settled per byte of blockchain data, reflecting how efficiently a protocol uses block space.
Economic Finality
The point at which reversing a blockchain transaction would require an economically irrational expenditure exceeding the potential gain.
Economic Security
Economic security measures the financial cost an attacker would need to bear in order to compromise a blockchain network.
Effective Fee Rate
The effective fee rate is the actual sat/vB cost of confirming a transaction after accounting for fee bumping, CPFP, and package evaluation.
EIP-1559
An Ethereum fee mechanism that burns a dynamic base fee and adds an optional priority tip, making gas costs more predictable.
Electrum Server
A backend service that indexes the Bitcoin blockchain to efficiently serve wallet queries, enabling lightweight clients without full node resources.
Elliptic Curve Cryptography (ECC)
Elliptic curve cryptography is the mathematical foundation behind Bitcoin's key pairs, enabling secure digital signatures with compact keys.
Eltoo
A proposed Lightning Network channel update mechanism using SIGHASH_ANYPREVOUT that simplifies state management by allowing any later state to replace any earlier state.
Embedded Finance
Integrating financial services like payments, lending, or insurance directly into non-financial apps and platforms.
Embedded Wallet
An embedded wallet is a crypto wallet integrated directly into an app so users can transact digital assets without switching applications.
Emission Schedule
An emission schedule defines how new tokens are created and distributed over time, controlling a cryptocurrency's inflation rate.
EMV Chip
The global smart card standard using embedded microchips for secure card-present transactions, replacing vulnerable magnetic stripes.
Encrypted Mempool
A proposed mechanism where pending transactions are encrypted until block inclusion, preventing front-running and MEV extraction.
Endpoint Security (Crypto)
Endpoint security in cryptocurrency protects the devices and applications where private keys are stored and transactions are signed.
Entropy (Cryptographic Randomness)
Entropy in cryptocurrency refers to the quality of randomness used to generate private keys and seed phrases that secure digital assets.
Ephemeral Anchor
An ephemeral anchor is a zero-value output anyone can spend, designed for fee bumping shared transactions like Lightning commitments.
Ephemeral Dust
Temporary dust outputs in Lightning commitment transactions that allow channels to use their full balance without reserving funds for on-chain fees.
ERC-1155
ERC-1155 is a multi-token Ethereum standard that supports both fungible and non-fungible tokens within a single smart contract.
ERC-20 (Token Standard)
ERC-20 is the Ethereum token standard defining a common interface for fungible tokens, enabling interoperability across DeFi.
ERC-721 (NFT Token Standard)
ERC-721 is the Ethereum token standard for non-fungible tokens, where each token has a unique ID and distinct ownership record.
Erlay
A proposed Bitcoin protocol improvement that reduces transaction relay bandwidth by 40% using set reconciliation instead of flooding.
Escape Hatch
An escape hatch is a mechanism allowing users to withdraw funds from a Layer 2 system back to the base layer, even if the L2 operator is unresponsive.
Escrow
Escrow is a financial arrangement where a trusted third party holds funds until predetermined conditions between buyer and seller are met.
ETF Premium and Discount
An ETF premium or discount occurs when the market price of ETF shares deviates from the net asset value of the underlying holdings.
EURC (Euro Coin)
A euro-backed stablecoin issued by Circle, providing a regulated digital euro for cross-border payments and DeFi.
Eurodollar
Eurodollars are US dollar deposits held in banks outside the United States, forming a massive offshore dollar market beyond Federal Reserve oversight.
Event-Driven Payment
A payment triggered automatically by a predefined condition or event rather than manual initiation, common in programmable money systems.
EVM Compatibility
EVM compatibility means a blockchain can execute Ethereum smart contracts and support Ethereum development tools without code changes.
Execution Layer
The component of a modular blockchain stack that processes transactions and executes smart contract logic, separate from consensus and data availability.
Exit Liquidity
Exit liquidity refers to the buyers who absorb selling pressure, often unknowingly purchasing assets from informed sellers.
Exit Scam
A fraud where a crypto project or exchange suddenly shuts down and disappears with users' deposited funds.
Extended Key (xprv/xpub)
A key plus chain code that enables deriving child keys in an HD wallet, with extended private keys (xprv) or public keys (xpub).
Fair Launch
A fair launch is a token distribution method with no pre-mine, pre-sale, or insider allocation, giving all participants equal access.
Faster Payments
The UK's real-time payment system processing domestic bank transfers in seconds, available 24/7 since 2008.
FATF Guidance
FATF guidance provides international standards for how countries should regulate virtual assets and VASPs to prevent money laundering and terrorism financing.
Faucet
A tool or website that distributes small amounts of cryptocurrency for free, typically used for testing on blockchain testnets.
FBO Account (For Benefit Of)
A bank account held by a fintech or platform on behalf of its end users, where funds belong to the users, not the company.
Fear and Greed Index
The Crypto Fear and Greed Index measures market sentiment on a 0-100 scale using volatility, volume, social media, and dominance data.
Fedimint
A federated custody and payment protocol for Bitcoin communities, using threshold cryptography to create community-run Bitcoin banks.
FedNow
The Federal Reserve's instant payment service enabling 24/7/365 real-time settlement between US banks and credit unions.
Fedwire
The Federal Reserve's real-time gross settlement system for high-value, time-critical US dollar payments between banks.
Fee Abstraction
Fee abstraction allows users to pay blockchain transaction fees in tokens other than the network's native currency, or have fees sponsored entirely by a third party.
Fee Bumping
Fee bumping is the practice of increasing a Bitcoin transaction's fee after broadcast to accelerate its confirmation during network congestion.
Fee Estimation
Algorithms that predict the optimal transaction fee rate for timely Bitcoin block inclusion based on mempool conditions.
Fee Market
The fee market is Bitcoin's mechanism where users compete for limited block space by offering transaction fees to incentivize miners.
Fee Rate
The price per unit of block space a Bitcoin transaction pays, measured in satoshis per virtual byte (sat/vB) to prioritize confirmation.
Fee Sniping
A theoretical mining attack where miners re-mine recent blocks to capture high-fee transactions, threatening finality.
Fee Spike
A sudden surge in Bitcoin transaction fees caused by high demand for limited block space, often triggered by market events or protocol activity.
Fiat Currency
Fiat currency is government-issued money not backed by a physical commodity, serving as the baseline for stablecoin pegs.
Fiat-Backed Stablecoin
A stablecoin maintaining its peg through reserves of fiat currency or fiat-equivalent assets held by a centralized custodian.
Finality
The point at which a transaction becomes irreversible and cannot be undone, varying by system design.
Finality Gadget
A protocol mechanism layered on top of a blockchain's consensus to provide deterministic finality checkpoints for confirmed blocks.
Finality Time
Finality time is the duration from transaction submission until a payment becomes irreversible and cannot be rolled back by the network.
Financial Inclusion
Financial inclusion means providing affordable access to banking, payments, credit, and savings to underserved populations worldwide.
Financial Messaging
Financial messaging is the standardized communication between banks that instructs, confirms, and reconciles payment transactions.
Finney Attack
A double-spend attack where a miner pre-mines a block containing a conflicting transaction and releases it after receiving goods.
Fiscal Sponsorship (Open Source)
Fiscal sponsorship provides legal and financial infrastructure for open-source Bitcoin projects to receive grants without forming a nonprofit.
Flash Crash
A flash crash is a sudden, extreme drop in asset prices that occurs within minutes and typically recovers quickly afterward.
Flash Loan
An uncollateralized DeFi loan that must be borrowed and repaid within the same blockchain transaction, enabling atomic arbitrage.
Flashbots
An infrastructure project providing tools for MEV extraction transparency, private transaction submission, and fair block building on Ethereum.
Float (Payments)
Money in transit between sender and receiver that hasn't yet settled, representing both a risk and a revenue opportunity.
Force Close
Unilaterally closing a Lightning channel by broadcasting the latest commitment transaction when the counterparty is unresponsive or malicious.
Forced Inclusion
Forced inclusion is a censorship-resistance mechanism allowing users to submit transactions directly to L1 if an L2 sequencer censors them.
Fork Choice Rule
A fork choice rule is the algorithm a blockchain node uses to select the canonical chain when multiple valid forks exist.
Formal Verification
Formal verification is a mathematical technique that proves a smart contract or protocol behaves exactly as specified under all possible inputs.
Forwarding Policy (Lightning)
A forwarding policy defines the rules a Lightning node uses to decide which routing requests to accept, including fee rates and size limits.
Four-Party Model
The four-party model is the standard card payment architecture involving the cardholder, merchant, issuer, and acquirer via a card network.
Fraud Proof
A mechanism where anyone can challenge an invalid state transition by proving the computation was incorrect, used in optimistic rollups.
Fraud Scoring
Fraud scoring assigns a numerical risk rating to a payment transaction based on behavioral signals, device data, and transaction patterns.
FRAX Stablecoin
A stablecoin that evolved from fractional-algorithmic design to fully collateralized, pioneering the hybrid stability approach.
Friendly Fraud
When a legitimate cardholder disputes a valid transaction, either intentionally (chargeback fraud) or due to confusion about the charge.
Front-Running
Exploiting advance knowledge of pending transactions to place profitable trades before them, common in DeFi and DEXs.
FROST (Flexible Round-Optimized Schnorr Threshold)
A threshold Schnorr signature scheme enabling t-of-n signing with just two communication rounds, optimal for distributed custody.
Full Node
A Bitcoin node that downloads and validates every block and transaction against consensus rules without trusting any third party.
Full RBF (Full Replace-by-Fee)
Full RBF is a mempool policy where any unconfirmed transaction can be replaced by a higher-fee version, regardless of opt-in signaling.
Full Reserve Banking
Full reserve banking requires financial institutions to hold 100% of customer deposits in liquid reserves rather than lending them out.
Fully Diluted Valuation (FDV)
A cryptocurrency's hypothetical market cap if all tokens in its maximum supply were in circulation at the current price.
Funding Rate
The periodic payment between long and short traders in perpetual futures markets that keeps the contract price anchored to the spot price.
Fungibility
Fungibility is the property where each unit of a currency is interchangeable and indistinguishable from any other unit of equal value.
FX Spread
The difference between the buy and sell price of a currency pair, representing a hidden cost in cross-border payments.
Gap Limit
The maximum number of consecutive unused addresses a wallet scans before assuming no more funds exist on derived addresses.
Gas Fee
A gas fee is the cost paid to execute transactions or smart contracts on blockchains like Ethereum, measured in computational work units.
Gas Limit
The gas limit is the maximum amount of computational work a transaction or block can consume on gas-based blockchains like Ethereum.
Gas Price
Gas price is the amount of cryptocurrency a user pays per unit of computation on blockchains like Ethereum, measured in gwei.
Gasless Transaction
A gasless transaction lets users interact with a blockchain without paying gas fees, with costs covered by a third party.
Gauge Voting
Gauge voting lets governance token holders direct protocol incentive emissions to specific liquidity pools, creating a market for yield allocation.
Generalized Channel
A generalized channel extends payment channels beyond simple value transfers to support arbitrary state transitions and conditional logic.
Genesis Block
The first block in the Bitcoin blockchain, mined by Satoshi Nakamoto on January 3, 2009, containing a famous newspaper headline.
GENIUS Act
Proposed US legislation establishing a federal framework for payment stablecoin issuance, reserves, and supervision.
GHO Stablecoin
Aave's decentralized stablecoin minted by borrowers using their Aave collateral, with interest rates set by governance.
Gossip Protocol (Lightning)
The peer-to-peer protocol Lightning nodes use to share information about channels, nodes, and fee policies across the network.
Governance Attack
A governance attack exploits a DAO's voting mechanism by acquiring enough governance tokens to pass malicious proposals that drain the treasury or alter protocol rules.
Governance Token
A crypto token granting holders voting rights over a protocol's parameters, upgrades, and treasury spending decisions.
Graph Analysis (Blockchain)
Blockchain graph analysis maps the flow of funds between addresses and entities to identify patterns, clusters, and suspicious activity.
Great Consensus Cleanup
The Great Consensus Cleanup is a proposed Bitcoin soft fork that fixes several long-standing consensus bugs and edge cases.
Greenlight
Blockstream's cloud-hosted Lightning node service where users keep their keys but the node runs in the cloud for reliability.
Gresham's Law
The economic principle that 'bad money drives out good,' explaining why people spend depreciating currency and hoard appreciating assets like Bitcoin.
Grid Trading
Grid trading places a series of buy and sell orders at fixed price intervals above and below a set price, profiting from natural market oscillations.
Griefing Attack
A griefing attack locks up a victim's funds or channel capacity without the attacker profiting, purely to cause disruption in payment networks.
Gwei
A denomination of Ether equal to one-billionth of an ETH, commonly used to express gas prices on the Ethereum network.
Hard Fork
A non-backward-compatible protocol change that creates a permanent chain split if not all nodes upgrade, dividing the network.
Hardened Derivation
An HD wallet key derivation method that prevents child public keys from being derived from the parent public key alone, protecting against key compromise cascades.
Hardware Security Module (HSM)
A dedicated physical device that generates, stores, and manages cryptographic keys in a tamper-resistant environment.
Hash Function
A hash function is a one-way mathematical algorithm that converts input data into a fixed-size output used in Bitcoin mining and transactions.
Hash Ribbon
The Hash Ribbon indicator tracks Bitcoin miner capitulation and recovery by comparing the 30-day and 60-day moving averages of hashrate.
Hash-Based Signatures
Digital signature schemes built entirely on hash functions, offering quantum resistance with minimal cryptographic assumptions.
Hashrate
The total computational power dedicated to Bitcoin mining, measured in hashes per second, indicating network security strength.
Hawala
An informal value transfer system based on trust networks, where money is sent without physical movement through local agents.
HD Wallet (Hierarchical Deterministic Wallet)
A wallet that derives all keys from a single master seed, enabling backup with just a seed phrase and organized key hierarchies.
Header Chain
The header chain is the sequence of block headers in a blockchain, verifiable independently without downloading full block data.
Headers-First Synchronization
Headers-first sync is a Bitcoin node strategy that downloads all block headers before fetching full blocks, enabling parallel and verified downloads.
HODL
A crypto community term meaning to hold an asset long-term rather than selling, originating from a misspelled Bitcoin forum post in 2013.
Hodl Invoice
A Lightning invoice where the receiver can delay settlement, enabling escrow-like functionality and conditional payments on the Lightning Network.
Hold Invoice
A hold invoice is a Lightning invoice where the recipient delays settling the payment, keeping funds locked until a condition is met.
Honeypot Contract
A honeypot contract is a malicious smart contract designed to appear profitable but traps users' funds once they interact with it.
Hot Wallet
A cryptocurrency wallet connected to the internet for convenient access and transactions, accepting higher security risk.
Howey Test
The Howey Test is the SEC's four-part legal framework for determining whether a digital asset qualifies as an investment contract (security).
HSM (Hardware Security Module)
Enterprise-grade hardware devices for generating, storing, and using cryptographic keys with FIPS 140-2/3 certification.
HTLC (Hash Time-Locked Contract)
A conditional payment mechanism using hash locks and time locks for trustless atomic transactions across payment channels.
Hybrid Collateral Ratio
A stablecoin design mechanism that dynamically adjusts the mix of asset-backed collateral and algorithmic stabilization to maintain price peg.
Hyperbitcoinization
Hyperbitcoinization is the theoretical tipping point where Bitcoin becomes the dominant global monetary system, displacing fiat currencies.
IBAN (International Bank Account Number)
The International Bank Account Number is a standardized format for identifying bank accounts across borders in 80+ countries.
Idempotency Key
An idempotency key is a unique identifier attached to a payment request that prevents duplicate transactions when a request is retried.
Idempotent Payment
A payment request designed so that repeating it produces the same result, preventing accidental duplicate charges.
IDO (Initial DEX Offering)
An initial DEX offering is a token launch method where new tokens are sold directly through a decentralized exchange launchpad.
Immutability
The property of blockchain data that makes it practically impossible to alter or delete once confirmed in a block.
Impermanent Loss
The opportunity cost LPs face when the price ratio of pooled tokens changes, resulting in less value than simply holding the tokens.
Inbound Liquidity
The capacity to receive Lightning payments, determined by how much of a channel's balance sits on the remote side.
Incentive Compatibility
A game-theoretic property where participants in a protocol are economically motivated to follow the rules rather than cheat.
Incentive Design
Incentive design in cryptocurrency aligns participant behavior with network goals by making honest participation more profitable than cheating.
Inflation Hedge
An asset that maintains or increases its purchasing power during periods of monetary inflation and currency debasement.
Initial Block Download (IBD)
The process of downloading and validating the entire Bitcoin blockchain when setting up a new full node, taking hours to days.
Initial Coin Offering (ICO)
An initial coin offering is a fundraising method where a crypto project sells newly created tokens to early investors in exchange for capital.
Inscription (Bitcoin)
A Bitcoin inscription embeds arbitrary data like images, text, or code directly into a Bitcoin transaction's witness data using the Ordinals protocol.
Instant Finality
A property where transactions are irreversible immediately upon confirmation, without waiting for additional block confirmations.
Instant Settlement
Settlement of payment transactions in real-time or near-real-time, eliminating the traditional multi-day delay between payment and fund availability.
Intent-Based Trading
A trading paradigm where users express desired outcomes and solvers compete to find the optimal execution path across venues.
Interac e-Transfer
Canada's real-time person-to-person payment system enabling instant bank transfers using email or phone number.
Interchange Fee
The fee paid by the merchant's bank to the cardholder's bank on each card transaction, set by card networks like Visa and Mastercard.
Interchange-Plus Pricing
A transparent payment processing pricing model where the merchant pays actual interchange plus a fixed markup from the processor.
Interoperability
Interoperability is the ability of different blockchain networks to communicate, share data, and transfer assets between each other.
Intrinsic Value
Intrinsic value refers to the fundamental worth of an asset based on its underlying utility, cash flows, or properties.
Invoice Encoding
Invoice encoding is the standard format for representing Lightning payment requests as human-readable strings with embedded payment details.
ISO 20022
A global messaging standard for financial transactions enabling richer, structured payment data across banks and payment systems.
ISO 8583
The international standard message format used by card networks for financial transaction authorization, clearing, and settlement.
Isolated Margin
Isolated margin limits the collateral at risk to a single trading position, preventing losses from spreading to other positions.
Issuer (Issuing Bank)
The bank that issues credit or debit cards to consumers, approving or declining transactions and bearing fraud risk.
JIT Channel (Just-in-Time)
A Lightning channel opened on-the-fly when a payment arrives, allowing users to receive their first payment without pre-existing channels.
Just-In-Time Liquidity (JIT)
A DeFi MEV strategy where liquidity is added to a pool moments before a large swap and removed immediately after to capture fees.
Justice Transaction
A penalty transaction that sweeps all funds from a cheating counterparty's Lightning channel, enforcing protocol rules and deterring fraud attempts.
Keeper Network
A keeper network is a decentralized system of bots that execute critical maintenance tasks for DeFi protocols in exchange for rewards.
Key Aggregation
Key aggregation combines multiple public keys into a single aggregate key, enabling multi-party signing that looks like a standard single-key transaction.
Key Ceremony
A formal, audited process for generating, distributing, or using high-value cryptographic keys with witnesses and security controls.
Key Derivation Function (KDF)
A key derivation function stretches a password or low-entropy input into a strong cryptographic key suitable for encryption or authentication.
Key Image
A cryptographic construct used in privacy coins like Monero to prevent double-spending without revealing which output was spent.
Key Management
The practices and systems for generating, storing, using, and backing up cryptographic keys that control digital assets.
Key Path Spend
A key path spend is the default way to spend a Taproot output, using a single Schnorr signature without revealing any script conditions.
Key Rotation
Periodically generating new cryptographic keys and migrating funds from old keys, limiting exposure from potential key compromise.
Key Share
A key share is one fragment of a cryptographic private key, distributed among multiple parties so that a threshold number must cooperate to sign.
Key Stretching
Key stretching is a cryptographic technique that strengthens a weak password or passphrase by applying a computationally expensive hash function repeatedly.
Keysend
A Lightning Network payment method that enables spontaneous payments without requiring an invoice from the recipient.
Know Your Transaction (KYT)
Compliance technology that monitors blockchain transactions in real time to detect suspicious activity and flag sanctioned addresses.
KYC/AML
Know Your Customer and Anti-Money Laundering regulations requiring financial institutions to verify identities and monitor for illicit activity.
Lattice-Based Cryptography
A family of post-quantum cryptographic constructions based on hard mathematical lattice problems resistant to quantum attacks.
Layer 0 (L0)
Layer 0 refers to the foundational infrastructure that enables multiple Layer 1 blockchains to be built, connected, and operated.
Layer 2
A protocol built on top of a base blockchain that processes transactions off-chain while inheriting the security of the underlying layer.
LDK (Lightning Dev Kit)
A flexible Lightning library that lets developers embed Lightning functionality directly into applications without running a standalone node.
Ledger (Accounting)
A systematic record of financial transactions organized into accounts, forming the foundation of all financial record-keeping.
Lending Protocol
A DeFi platform enabling permissionless borrowing and lending of crypto assets with algorithmic interest rates set by supply and demand.
Leverage
Leverage allows traders to control larger positions using borrowed funds, amplifying both potential gains and losses.
Lightning Address
An email-like identifier (user@domain.com) that resolves to a Lightning invoice, making payments as easy as sending an email.
Lightning Channel
A two-party payment channel funded by an on-chain Bitcoin transaction that enables unlimited off-chain transactions between participants.
Lightning Gateway
A Lightning gateway connects non-Lightning protocols to the Lightning Network, enabling interoperability between different payment systems.
Lightning Invoice
A payment request containing the amount, destination, payment hash, and routing hints needed to send a Lightning payment.
Lightning Network vs Spark
A comparison of the two Bitcoin Layer 2 approaches: Lightning's payment channels vs Spark's statechain-based architecture.
Lightning Service Provider (LSP)
A service that manages Lightning channels and liquidity on behalf of users, enabling seamless mobile wallet experiences.
Lightweight Client
A blockchain client that verifies transactions using block headers and Merkle proofs rather than downloading the full chain.
Limit Order (DeFi)
A DeFi order to swap tokens at a specified price or better, executed when market conditions meet the trader's terms.
Lindy Effect
The observation that the longer a technology or idea has survived, the longer its remaining life expectancy tends to be.
Linearization (Mempool)
Linearization is the process of ordering related mempool transactions to maximize the total fee captured within block weight constraints.
Liquid Network
A federated Bitcoin sidechain by Blockstream offering confidential transactions, faster settlement, and issued assets for traders and institutions.
Liquid Restaking
A protocol that takes already-staked assets and restakes them to secure additional protocols, earning multiple layers of yield while maintaining token liquidity.
Liquid Staking
A DeFi mechanism that issues tradeable tokens representing staked assets, unlocking liquidity while maintaining staking rewards.
Liquidation (DeFi)
The forced sale of a borrower's collateral when its value drops below the required ratio, protecting lenders from bad debt.
Liquidation Cascade
A chain reaction of forced collateral liquidations triggered when market crashes push multiple DeFi vaults below their minimum collateralization thresholds simultaneously.
Liquidation Price
The liquidation price is the asset price at which a leveraged position's margin falls below the maintenance requirement, triggering forced closure.
Liquidity Ads
A protocol for Lightning nodes to advertise and sell channel liquidity in a decentralized marketplace.
Liquidity Bootstrapping Pool (LBP)
A token launch mechanism using weighted AMM pools that shift over time, enabling fair price discovery without front-running.
Liquidity Fragmentation
The spreading of trading liquidity across multiple chains, DEXs, and pools, making it harder to execute large trades efficiently.
Liquidity Lease
A liquidity lease is a time-bound agreement where a Lightning node rents channel capacity to another node for an upfront or periodic fee.
Liquidity Lock
A liquidity lock is a mechanism that prevents liquidity pool tokens from being withdrawn for a specified time period, protecting investors from rug pulls.
Liquidity Mining
Liquidity mining is a DeFi incentive program that rewards users with tokens for providing liquidity to a protocol's trading pools.
Liquidity Pool
A liquidity pool is a collection of crypto assets locked in a smart contract that provides liquidity for decentralized trading and lending.
Liquidity Provider (LP)
A user who deposits tokens into a DeFi protocol's liquidity pool, earning fees from trades executed against their capital.
Liveness
A blockchain property guaranteeing that valid transactions will eventually be included in the chain, even if some validators are offline.
LN-Symmetry (Eltoo)
A proposed Lightning channel update mechanism using SIGHASH_ANYPREVOUT that replaces penalty-based revocation with simpler state updates.
LND (Lightning Network Daemon)
The most widely deployed Lightning implementation, built by Lightning Labs in Go, powering the majority of Lightning nodes.
LNHANCE
LNHANCE is a Bitcoin soft fork proposal bundling OP_CTV, OP_CHECKSIGFROMSTACK, and OP_INTERNALKEY to enable better Lightning and vault constructions.
LNURL
A set of HTTP-based protocols extending Lightning with features like auth, pay, withdraw, and channel requests via simple URLs.
Locktime (nLockTime)
A transaction-level field that prevents a Bitcoin transaction from being included in a block until a specified time or block height.
Long-Term Holder (LTH)
An on-chain analytics classification for wallet addresses that have held Bitcoin for more than 155 days without transacting.
Longest Chain Rule
The longest chain rule dictates that Bitcoin nodes treat the chain with the most cumulative proof-of-work as the valid blockchain.
Loop In/Out
Submarine swap mechanisms for moving funds between on-chain Bitcoin and Lightning Network without custody, enabling non-custodial liquidity management.
LUSD (Liquity USD)
An immutable, governance-free stablecoin backed only by ETH collateral, generated through the Liquity protocol.
Mainnet
A mainnet is the primary live blockchain network where real transactions with economic value are broadcast and recorded.
Maker-Taker Fee Model
The maker-taker fee model charges lower fees to limit orders that add liquidity (makers) and higher fees to market orders that remove it (takers).
Man-in-the-Middle Attack (MITM)
An attack where an adversary secretly intercepts and potentially alters communications between two parties in a crypto transaction.
Margin Trading
Margin trading lets crypto traders borrow funds to increase their position size, amplifying both potential gains and losses.
Market Capitalization (Market Cap)
Market capitalization is the total value of a cryptocurrency, calculated by multiplying current price by total circulating supply.
Market Cycle
The recurring pattern of expansion and contraction in cryptocurrency markets, often correlated with Bitcoin's four-year halving events.
Market Depth
Market depth measures the volume of buy and sell orders at each price level in an order book, indicating a market's ability to absorb large trades.
Market Maker
A participant that continuously quotes buy and sell prices for an asset, providing liquidity and earning the bid-ask spread.
Market Manipulation
Market manipulation is the deliberate act of artificially influencing the price or volume of an asset for personal gain.
Market Order
A market order is an instruction to buy or sell a cryptocurrency immediately at the best available price in the order book.
Market Sentiment
Market sentiment is the overall attitude of investors toward a cryptocurrency or the market as a whole, driven by news, social media, and price action.
MAST (Merkelized Alternative Script Trees)
A Taproot feature enabling multiple spending conditions organized in a Merkle tree, revealing only the used condition on-chain.
Masternode
A specialized full node that performs advanced network functions like instant transactions and governance voting, requiring collateral.
Maturity Date (Stablecoin Reserves)
The maximum holding period for reserve assets backing a stablecoin, set at 93 days for US Treasuries under the GENIUS Act.
Max Supply
Max supply is the hard cap on the total number of tokens that will ever exist for a given cryptocurrency, like Bitcoin's 21 million limit.
Medium of Exchange
A medium of exchange is any asset widely accepted in transactions, enabling trade without the need for direct barter between parties.
Mempool
Each Bitcoin node's waiting area for unconfirmed transactions, where transactions compete for block inclusion based on fee rates.
Mempool Policy
Mempool policy is the set of rules each Bitcoin node applies to decide which unconfirmed transactions to accept, relay, and evict from its local mempool.
Merchant Category Code (MCC)
A merchant category code is a four-digit number assigned by card networks to classify businesses by the type of goods or services they sell.
Merchant Discount Rate (MDR)
The total percentage fee a merchant pays per card transaction, comprising interchange, scheme fees, and acquirer markup.
Merchant of Record (MoR)
The entity that appears on a customer's bank statement and bears responsibility for the transaction, taxes, and disputes.
Merged Mining
Merged mining allows miners to simultaneously mine multiple blockchains using the same proof-of-work, securing child chains without extra energy.
Merkle Mountain Range (MMR)
A Merkle Mountain Range is an append-only data structure that proves membership in a growing dataset without rebuilding the entire tree.
Merkle Patricia Trie
A Merkle Patricia trie is the data structure Ethereum uses to store account states, combining hash verification with efficient key-value lookups.
Merkle Proof
A Merkle proof is a compact cryptographic proof that a specific transaction is included in a block without downloading all block data.
Merkle Root
A Merkle root is the single top-level hash in a Merkle tree that cryptographically summarizes all transactions included in a Bitcoin block.
Merkle Tree
A binary tree of hashes used in Bitcoin blocks to efficiently prove transaction inclusion with minimal data.
Message Authentication Code (MAC)
A message authentication code is a cryptographic tag that verifies both the integrity and authenticity of a message using a shared secret key.
MEV (Maximal Extractable Value)
The profit available by reordering, inserting, or censoring transactions within a block, extracted by validators and searchers.
MEV Supply Chain
The ecosystem of searchers, builders, and validators that discover, extract, and distribute value from transaction ordering on blockchains like Ethereum.
MEV-Boost
MEV-Boost is middleware that lets Ethereum validators outsource block building to specialized builders, capturing maximal extractable value revenue.
MiCA (Markets in Crypto-Assets)
The EU's comprehensive crypto regulation framework covering stablecoins, exchanges, and service providers, effective from 2024.
Micropayment
A micropayment is a financial transaction for a very small amount, typically under one dollar, enabled by low-fee payment networks like Lightning.
Minimum Relay Fee
The minimum relay fee is the lowest fee rate a Bitcoin node will accept to relay an unconfirmed transaction across the peer-to-peer network.
Mining (Bitcoin)
Bitcoin mining is the process of using computational power to validate transactions, secure the network, and mint new bitcoins.
Mining Pool
A group of miners combining hashrate to find blocks more frequently and share rewards proportionally, reducing income variance.
Mining Profitability
Mining profitability measures whether the revenue from mining cryptocurrency exceeds the costs of hardware, electricity, and operations.
Mining Reward
The total compensation miners receive per block: the block subsidy (newly created BTC) plus all transaction fees included in the block.
Miniscript
A structured subset of Bitcoin Script that enables analysis, composition, and generic signing of spending conditions.
Mint/Burn Mechanism
The process of creating new stablecoin tokens when assets are deposited and destroying them upon redemption.
Mobile Money
A phone-based financial service enabling unbanked users to store, send, and receive money without a traditional bank account.
Modular Blockchain
A blockchain architecture separating execution, consensus, data availability, and settlement into specialized layers for scalability.
Monetary Policy
Monetary policy is how a central bank manages money supply and interest rates to influence economic activity, inflation, and employment.
Monetary Premium
The portion of an asset's market value derived from its perceived monetary properties rather than its industrial or utility value.
Money Market (DeFi)
A DeFi money market is a protocol that facilitates permissionless lending and borrowing of crypto assets through smart contracts.
Money Services Business (MSB)
A FinCEN classification for businesses involved in money transmission, currency exchange, check cashing, or stored value.
Money Transfer Operator (MTO)
A non-bank company specializing in cross-border remittances, like Western Union and Wise, often serving unbanked populations.
Money Transmitter License
A state-level US license required to transmit money or provide payment services, with each state having its own requirements.
Money Velocity
Money velocity measures how frequently a unit of currency changes hands within an economy over a given period, indicating economic activity.
MPC Wallet
A wallet using multi-party computation to distribute key material across multiple parties, eliminating single points of failure.
MPP (Multipath Payments)
A Lightning payment split across multiple routes that recombines atomically at the destination for improved reliability.
Multi-Currency Account
A financial account that holds and transacts in multiple currencies simultaneously, reducing the need for foreign exchange conversions.
Multi-Party Computation (MPC)
Multi-party computation lets multiple parties jointly compute a function over their private inputs without revealing those inputs to each other.
Multi-Path Payments (MPP)
A Lightning feature that splits a single payment across multiple routes to improve success rates and enable larger payments.
Multisig Wallet
A Bitcoin wallet requiring multiple private keys to authorize transactions, providing shared control and eliminating single points of failure.
MuSig2 (Multi-Signature Scheme)
MuSig2 is a Schnorr-based multi-signature protocol that produces a single aggregated signature indistinguishable from a regular signature.
MVRV Ratio (Market Value to Realized Value)
The MVRV ratio compares Bitcoin's market cap to its realized cap, indicating whether holders are in aggregate profit or loss.
Nakamoto Consensus
Nakamoto consensus is the probabilistic agreement mechanism Bitcoin uses, combining proof-of-work mining with the longest-chain rule.
Native Token
A native token is the base currency of a blockchain network, used to pay transaction fees and incentivize validators.
Net Asset Value (NAV)
Net asset value is the per-share value of a fund calculated by dividing total assets minus liabilities by the number of outstanding shares.
Network Congestion
Network congestion occurs when transaction demand exceeds a blockchain's processing capacity, causing higher fees and longer confirmation times.
Network Effect
A network effect occurs when a product or protocol becomes more valuable as more people use it, driving exponential adoption growth.
Network Fee
A network fee is the cost paid to blockchain validators or miners for processing and confirming a transaction on the network.
Network Partition
A network failure where groups of nodes become isolated from each other, potentially causing temporary chain forks or consensus stalls.
Network Token
A card network-issued token replacing the actual card number, improving authorization rates and reducing fraud across merchants.
Network Tokenization
A card network service that replaces card numbers with network-level tokens, improving security and enabling higher authorization rates.
NFC (Near Field Communication)
A short-range wireless technology enabling contactless payments by transmitting data between devices within a few centimeters.
NFT (Non-Fungible Token)
A unique digital asset with verifiable ownership on blockchain, representing art, collectibles, gaming items, or real-world assets.
Node as a Service (NaaS)
Node as a Service provides hosted blockchain node infrastructure so developers can access on-chain data without running their own nodes.
Node Operator
An individual or entity that runs blockchain node software, contributing to network validation, relay, and decentralization.
Nonce
A number used once in Bitcoin mining that miners iterate through to find a block hash below the difficulty target.
Nonce Reuse Vulnerability
Nonce reuse is a critical cryptographic vulnerability where reusing a random number during digital signing exposes the signer's private key.
Nostr (Notes and Other Stuff Transmitted by Relays)
Nostr is a decentralized protocol using cryptographic keypairs and relays, adopted by the Bitcoin community for censorship-resistant social media.
Nostr Wallet Connect (NWC)
Nostr Wallet Connect is a protocol that lets apps control a Lightning wallet remotely using Nostr keypairs for authentication and encrypted messaging.
Nostro and Vostro Accounts
Mirror accounts held between correspondent banks: a nostro (our account at your bank) and vostro (your account at our bank).
Nothing-at-Stake Problem
The nothing-at-stake problem describes a proof-of-stake vulnerability where validators can cheaply vote on multiple competing chain forks.
NVT Ratio (Network Value to Transactions)
The NVT ratio divides Bitcoin's market cap by its daily on-chain transaction volume, functioning as a crypto PE ratio.
OFAC Sanctions
OFAC sanctions are U.S. Treasury restrictions that prohibit financial transactions with designated individuals, entities, and countries.
Off-Chain Governance
A governance model where protocol decisions are made through community discussion, developer consensus, and social coordination rather than on-chain voting mechanisms.
Off-Chain Protocol
Any system that processes transactions outside the main blockchain while periodically anchoring state or proofs to the base layer.
Omnibus Wallet
A single blockchain wallet holding funds for multiple users, with individual balances tracked in an off-chain database.
On-Chain Governance
A governance model where protocol changes are proposed, voted on, and enacted directly through blockchain transactions.
On-Chain Metrics
On-chain metrics are blockchain-derived data points like active addresses, transaction volume, and holder behavior used for market analysis.
On-Chain vs Off-Chain
On-chain transactions are recorded directly on the blockchain, while off-chain transactions occur on secondary layers and settle later.
On-Ramp / Off-Ramp
Services converting between fiat currency and cryptocurrency, enabling users to enter and exit the crypto economy.
Onion Message
A Lightning Network messaging protocol that uses onion encryption to relay data between nodes without requiring a payment channel path.
Onion Routing
A layered encryption technique where each routing node can only decrypt its own instructions, preserving sender and receiver privacy.
OP_CAT (Proposed)
A proposed Bitcoin opcode to concatenate two stack elements, potentially enabling covenants and advanced smart contracts on Bitcoin.
OP_CHECKLOCKTIMEVERIFY (OP_CLTV)
A Bitcoin Script opcode that prevents an output from being spent until a specified block height or timestamp.
OP_CHECKMULTISIG
A legacy Bitcoin Script opcode for m-of-n multisignature verification, replaced by OP_CHECKSIGADD in Tapscript.
OP_CHECKSEQUENCEVERIFY (OP_CSV)
A Bitcoin Script opcode that enforces a relative timelock, requiring a minimum number of blocks since the input was confirmed.
OP_CHECKSIG
The Bitcoin Script opcode that verifies a digital signature against a public key, the most fundamental operation in Bitcoin transactions.
OP_CHECKSIGFROMSTACK (CSFS)
OP_CHECKSIGFROMSTACK is a proposed Bitcoin opcode that verifies a signature against an arbitrary message from the stack, enabling covenants.
OP_IF / OP_NOTIF
Bitcoin Script flow control opcodes that enable conditional execution paths, essential for complex contracts like HTLCs.
OP_RETURN
A Bitcoin script opcode that marks an output as provably unspendable, commonly used to embed arbitrary data in transactions.
OP_TXHASH
OP_TXHASH is a proposed Bitcoin opcode that pushes a configurable hash of the spending transaction onto the stack for covenant logic.
OP_VAULT (Proposed)
A proposed Bitcoin opcode specifically designed to enable vault contracts with secure recovery and withdrawal delay mechanisms.
Open Banking
Regulatory frameworks requiring banks to share customer financial data with authorized third parties via secure APIs.
Open Finance
Open finance extends open banking beyond payments to include investments, insurance, pensions, and lending via standardized APIs.
Open Interest
Open interest measures the total number of outstanding derivative contracts that have not been settled, signaling market conviction and liquidity.
Open-Loop Payment System
A payment network where cards or credentials are accepted across multiple merchants and institutions, like Visa or Mastercard.
Optimistic Rollup
A Layer 2 scaling solution that assumes transactions are valid by default and uses fraud proofs to handle disputes.
Oracle Extractable Value (OEV)
Value captured by exploiting the latency between off-chain price updates and on-chain oracle submissions in DeFi protocols.
Oracle Manipulation
An attack vector where malicious actors distort price feeds used by smart contracts, often to trigger unjust liquidations or exploit arbitrage in collateralized protocols.
Order Book DEX
A decentralized exchange matching buy and sell orders at specific prices, offering familiar trading mechanics without centralized custody.
Ordinals
A protocol for inscribing arbitrary data to individual satoshis, creating Bitcoin-native digital artifacts and NFTs.
Orphan Block (Stale Block)
A valid block that is not part of the longest chain because another block at the same height was accepted first by the network.
Ossification
The gradual process by which a blockchain protocol becomes increasingly resistant to change as its network and dependencies grow.
OTC Trading (Over-the-Counter)
OTC trading lets buyers and sellers exchange crypto directly without a public order book, enabling large block trades with minimal price impact.
Outbound Liquidity
Outbound liquidity is the capacity a Lightning Network node has to send payments through its channels to other nodes.
Output Descriptor
A standardized format describing how Bitcoin addresses are derived, enabling precise wallet backup and restoration across different software.
Overcollateralization
Requiring collateral worth more than the borrowed or minted amount to provide a safety buffer against price volatility.
P2PKH (Pay-to-Public-Key-Hash)
The original Bitcoin address format starting with '1', paying to the hash of a public key for basic single-signature transactions.
P2SH (Pay-to-Script-Hash)
A Bitcoin address format starting with '3' that pays to the hash of a script, enabling multisig and complex spending conditions.
P2TR (Pay-to-Taproot)
The Taproot address format starting with 'bc1p', supporting both key-path and script-path spending with enhanced privacy.
P2WPKH (Pay-to-Witness-Public-Key-Hash)
The native SegWit address format for single-signature transactions, starting with 'bc1q' and offering the lowest fees before Taproot.
P2WSH (Pay-to-Witness-Script-Hash)
The native SegWit address format for script-based transactions like multisig, offering larger script capacity than P2SH.
Package Relay
Package relay is a Bitcoin protocol upgrade allowing nodes to evaluate groups of related transactions together for mempool acceptance.
Paper Wallet
A paper wallet is a physical document containing a cryptocurrency private key and address, used as an offline cold storage method.
Parallel Execution
Parallel execution processes multiple blockchain transactions simultaneously rather than sequentially, dramatically increasing throughput.
Passkeys (WebAuthn/FIDO2)
A passwordless authentication standard using public key cryptography, increasingly adopted for crypto wallet access.
Passphrase (25th Word)
An optional password added to a seed phrase that derives an entirely different set of keys, enabling plausible deniability.
Path-Finding Algorithm
A path-finding algorithm discovers the optimal route for a payment across a network of channels, balancing fees, reliability, and latency.
Pay-Per-Share (PPS)
Pay-per-share is a mining pool payout method that pays miners a fixed reward for each valid share submitted, regardless of whether the pool finds a block.
Pay-to-Anchor (P2A)
A minimal Bitcoin output type designed for efficient fee bumping of pre-signed transactions using child-pays-for-parent.
PayJoin
A privacy-enhancing Bitcoin payment where both sender and receiver contribute inputs, breaking chain analysis assumptions.
Paymaster
A paymaster is a smart contract that sponsors gas fees on behalf of users, enabling gasless transactions in account abstraction systems.
Payment Aggregator
A company that bundles many small merchants under a single merchant account, simplifying onboarding but sharing risk exposure.
Payment Channel
A payment channel is a two-party off-chain protocol that enables unlimited transactions settled by a single on-chain open and close.
Payment Channel Network
A mesh of interconnected payment channels enabling multi-hop transactions, with Lightning Network being the largest example.
Payment Facilitator (PayFac)
A company that processes payments on behalf of sub-merchants under its own merchant account, simplifying onboarding.
Payment Finality
The point at which a payment becomes irrevocable and cannot be recalled, varying dramatically across different payment systems.
Payment Fraud
Criminal exploitation of payment systems through identity theft, account takeover, counterfeit cards, or social engineering.
Payment Gateway
Software that securely transmits payment data from a merchant's checkout to the payment processor for authorization.
Payment Hash
A SHA-256 hash of the preimage that serves as the conditional lock for an HTLC payment in Lightning.
Payment Idempotency
Payment idempotency ensures that submitting the same payment request multiple times produces only one charge, preventing duplicates.
Payment Initiation Service (PIS)
A regulated service under PSD2 that initiates bank payments on behalf of users, enabling checkout without card networks.
Payment Netting
Payment netting is the process of offsetting multiple obligations between parties to reduce the number and value of actual settlements.
Payment Orchestration
Software that routes transactions across multiple payment providers to optimize authorization rates, costs, and redundancy.
Payment Orchestration Platform
A middleware layer that connects to multiple PSPs, acquirers, and payment methods to optimize routing, reduce costs, and increase resilience.
Payment Preimage
The secret value that, when hashed, matches a payment hash, serving as cryptographic proof that a Lightning payment was received.
Payment Probe
A technique to discover channel balances and route viability by sending payments designed to fail at the destination.
Payment Processor
A company that handles the technical routing of card transactions between merchants, card networks, and issuing banks.
Payment Rails
The underlying infrastructure and networks that move money between parties, from legacy card networks to modern blockchain systems.
Payment Reversal
A payment reversal is the return of funds from a completed transaction back to the payer, occurring through voids, refunds, or chargebacks.
Payment Scheme
A payment scheme is the governing organization and rulebook behind a payment network, such as Visa, Mastercard, or a local debit system.
Payment Service Provider (PSP)
A company offering merchants the technology and banking relationships to accept electronic payments across multiple methods.
Payment Settlement Cycle
The time between a payment transaction and when the merchant receives the funds, typically T+1 to T+3 for card payments.
Payment Streaming
Payment streaming continuously transfers money in real time, paying per second rather than in discrete lump sums on fixed schedules.
Payment Surcharging
Adding an extra fee at checkout when customers pay by card, passing processing costs to the cardholder rather than absorbing them.
Payment Switch
A central routing system that directs payment transactions between acquirers, issuers, and card networks for authorization and settlement.
PCI DSS
The Payment Card Industry Data Security Standard, a set of requirements for organizations that handle credit card data.
Pedersen Commitment
A cryptographic commitment scheme that hides a value while allowing mathematical operations, used in confidential transactions.
Peer Discovery
The process by which a Bitcoin node finds and connects to other nodes on the network, using DNS seeds, addr messages, and gossip.
Peer-to-Peer Network (P2P)
A peer-to-peer network is a distributed system where nodes communicate directly with each other without relying on a central server.
Peg Mechanism
The system of incentives, arbitrage, and backing that maintains a stablecoin's price at its target value.
Peg Stability Module (PSM)
A Peg Stability Module allows direct 1:1 swaps between a stablecoin and approved collateral assets to maintain price stability.
Penalty Transaction
A transaction that claims all funds in a Lightning channel when a counterparty broadcasts an outdated commitment transaction, enforcing honest behavior through severe financial consequences.
PEP (Politically Exposed Person)
An individual in a prominent public position who presents elevated risk for bribery and corruption in financial compliance screening.
Permissioned Blockchain
A permissioned blockchain restricts who can participate in the network, validate transactions, or access data.
Permissionless
A permissionless system allows anyone to participate without approval, a core property of public blockchains like Bitcoin.
Permit Signature (EIP-2612)
An ERC-20 token approval mechanism that uses off-chain signatures instead of on-chain transactions, enabling gasless approvals.
Permitted Payment Stablecoin
A regulatory classification under the GENIUS Act for stablecoins issued by licensed entities that meet federal reserve and compliance requirements.
Perpetual Futures
Crypto derivative contracts with no expiry date that track an underlying asset's price through funding rate payments between longs and shorts.
Phantom Invoice
A phantom invoice is a Lightning invoice that can be paid to any node in a set, enabling load balancing and high availability across multiple nodes.
Phishing Attack
A social engineering attack using fake websites, emails, or messages to trick users into revealing private keys, seed phrases, or passwords.
PIX Payments
Brazil's instant payment system launched by the central bank, enabling free 24/7 transfers and becoming the country's dominant payment method.
Plasma
An early Ethereum Layer 2 design using exit games for security, largely superseded by rollups but influential in L2 research.
Points Program
A points program rewards early users with off-chain points that are expected to convert into governance tokens at a future airdrop, incentivizing pre-launch usage.
Post-Quantum Cryptography (PQC)
Cryptographic algorithms designed to resist attacks from quantum computers, ensuring long-term security for Bitcoin and digital assets.
Pre-Authorization
Pre-authorization is a payment hold that verifies funds availability and reserves an amount on a cardholder's account before final capture.
Pre-Mine
A pre-mine is the creation and allocation of cryptocurrency tokens before a project's public launch, typically reserved for founders and investors.
Precision Decay
Cumulative rounding errors in fixed-point arithmetic during multi-hop swaps that can be exploited to drain liquidity pools; a vulnerability class flagged in numerous DeFi security audits.
Preconfirmation
A preconfirmation is an early commitment from a block proposer or sequencer that a transaction will be included in a future block, providing near-instant assurance before on-chain finalization.
Preimage
The secret value that, when hashed, produces the payment hash and unlocks an HTLC to claim a Lightning payment.
Price Feed
A price feed is a data stream that provides real-time or near-real-time asset prices to smart contracts, DeFi protocols, and trading systems.
Price Impact
Price impact is the change in an asset's market price caused by the size of a trade relative to available liquidity in a pool or order book.
Priority Fee (Tip)
An optional fee paid directly to block producers above the base fee to incentivize faster transaction inclusion in EIP-1559 networks.
Private Channel (Unannounced)
A Lightning channel not broadcast to the network gossip protocol, known only to the two participants and used via route hints.
Private Key
A secret 256-bit number that controls Bitcoin ownership, used to sign transactions proving authorization to spend funds.
Private Order Flow
Transactions sent directly to block builders instead of the public mempool to avoid front-running and MEV extraction.
Probabilistic Finality
A finality model where transaction reversals become exponentially less likely with each additional block confirmation but are never mathematically impossible.
Probing
A technique used to discover Lightning Network channel balances and network topology by sending fake payments that reveal routing information.
Programmable Money
Digital currency with embedded rules governing how, when, and by whom it can be spent, enabling automated financial logic.
Programmable Payments
Programmable payments use conditional logic to automate when, how, and to whom funds are released based on predefined rules or events.
Proof of Authority (PoA)
Proof of Authority is a consensus mechanism where approved validators stake their reputation and identity rather than economic collateral.
Proof of Burn (PoB)
Proof of Burn is a consensus mechanism where participants permanently destroy tokens by sending them to an unspendable address, earning the right to validate blocks proportional to the amount burned.
Proof of History (PoH)
Proof of History is a cryptographic clock that creates a verifiable ordering of events without requiring network-wide timestamp consensus.
Proof of Stake (PoS)
Proof of stake is a consensus mechanism where validators lock up cryptocurrency as collateral to propose and attest to new blocks.
Proof of Work (PoW)
Proof of work is a consensus mechanism where miners expend computational energy to validate transactions and secure the blockchain.
Proposer-Builder Separation (PBS)
A blockchain design separating block construction (builders) from block proposal (validators) to manage MEV distribution.
Proto-Danksharding
Proto-Danksharding is the Ethereum upgrade (EIP-4844) introducing blob transactions as a stepping stone to full data sharding.
Protocol Fee
A protocol fee is a charge collected by a decentralized protocol's smart contracts, often directed to the treasury or token holders.
Protocol-Owned Liquidity (POL)
Protocol-owned liquidity is a DeFi model where a protocol owns its own trading liquidity instead of renting it from yield farmers.
Proxy Contract
A proxy contract delegates calls to an implementation contract, enabling smart contract upgrades without changing the deployed address.
Pruned Node
A Bitcoin full node that discards old block data after validation, significantly reducing storage requirements while maintaining full validation.
PSBT (Partially Signed Bitcoin Transaction)
A standardized format for constructing and signing Bitcoin transactions across multiple parties or devices.
PSD2/PSD3 (Payment Services Directive)
PSD2 and PSD3 are EU regulations requiring banks to share payment data via APIs, enabling third-party fintech services.
PTLC (Point Time-Locked Contract)
An improved conditional payment mechanism using Schnorr signatures and adaptor signatures instead of hash locks.
Public Key
A point on the secp256k1 elliptic curve derived from a private key, used to verify signatures and generate Bitcoin addresses.
Puell Multiple
The Puell Multiple compares daily Bitcoin mining revenue to its 365-day moving average, identifying periods of miner stress or excessive profitability.
Pull Payment
A payment where the recipient initiates the charge against the payer's account, common in subscriptions and recurring billing.
Purchasing Power
The quantity of goods and services one unit of money can buy, a measure that declines as inflation increases over time.
Push Payment
A payment initiated and authorized by the sender, giving them full control over when and how much to send.
PYUSD (PayPal USD)
PayPal's dollar-backed stablecoin issued by Paxos, available to PayPal and Venmo users for payments and transfers.
QR Code Payments
Payment transactions initiated by scanning a QR code, dominant in Asia and Latin America for mobile point-of-sale payments.
Qualified Custodian
A qualified custodian is a regulated financial institution authorized to hold customer assets, required by law for investment advisers managing client funds.
Rapid Gossip Sync (RGS)
Rapid Gossip Sync is a protocol that lets mobile Lightning wallets download a compressed network graph snapshot instead of syncing gossip messages.
Real Yield
Real yield is DeFi protocol revenue distributed to token holders from actual fees and profits, not from inflationary token emissions.
Real-Time Payments
Payment systems that transfer and settle funds within seconds, available 24/7, replacing batch-processed legacy rails.
Real-World Assets (RWA)
Traditional financial assets like Treasury bills, bonds, and real estate tokenized on blockchain for DeFi composability.
Realized Capitalization
Realized cap values each Bitcoin at the price it last moved on-chain, providing a more grounded alternative to traditional market cap.
Rebasing Token
A token that automatically adjusts wallet balances to reflect yield or maintain a peg, changing supply rather than price.
Reconciliation
The process of matching internal records with external payment data to ensure all transactions are accurately accounted for.
Recurring Billing
Automatically charging a customer at regular intervals for subscriptions and memberships, requiring stored payment credentials.
Reentrancy Attack
A reentrancy attack exploits a smart contract by repeatedly calling back into it before the first execution completes, draining funds.
RegTech (Regulatory Technology)
RegTech uses technology to help financial institutions automate regulatory compliance, reporting, and risk management processes.
Regulatory Sandbox
A regulatory sandbox is a controlled environment where fintech and crypto companies can test new products under relaxed regulatory oversight.
Rehypothecation
Rehypothecation is reusing collateral posted by a borrower as collateral for another loan, creating chains of leveraged obligations.
Relayer
A relayer is a node or service that forwards transactions or messages between blockchain networks or between users and protocols.
Remittance Corridor
A specific geographic route for cross-border money transfers, with costs and speeds varying dramatically by corridor.
Replace-By-Fee (RBF)
A Bitcoin mempool policy allowing unconfirmed transactions to be replaced with higher-fee versions.
Replacement Cycling
A Lightning Network attack where an adversary replaces a victim's HTLC timeout transaction in the mempool through repeated RBF, potentially stealing routed funds.
Replay Attack
Reusing a valid transaction or signature on a different chain or context where it wasn't intended.
Request to Pay
A payment messaging standard that lets billers send payment requests directly to a payer's bank app for approval.
Reserve Proof
Cryptographic or audit-based evidence that a stablecoin issuer holds sufficient assets to back all outstanding tokens.
Restaking
Restaking allows staked crypto assets to secure additional protocols simultaneously, extending the base chain's economic security to new services.
Revocation Key
A cryptographic key derived during Lightning Network channel updates that allows a counterparty to claim all channel funds if an old, revoked commitment transaction is broadcast.
RGB Protocol
A Bitcoin Layer 2 for smart contracts and token issuance using client-side validation, keeping contract data off-chain.
Ring Signature
A ring signature is a cryptographic scheme where any member of a group can sign a message, hiding the actual signer among decoys.
RIPEMD-160
A 160-bit hash function used in Bitcoin address generation to shorten public key hashes, combined with SHA-256 in HASH160.
Risk Scoring
Assigning a numerical fraud probability to each transaction using machine learning models analyzing hundreds of data signals.
Rollup
A Layer 2 scaling solution that executes transactions off-chain and posts compressed data or proofs to the base layer for security.
Route Hints
Routing information embedded in Lightning invoices that enable payments to nodes with private or unannounced channels.
Routing Attack
Attacks targeting Lightning Network payment routing, including fee manipulation, channel jamming, and balance probing.
Routing Fees
The fees charged by Lightning nodes to forward payments through their channels, consisting of a base fee and a proportional fee.
Routing Node (Lightning Network)
A Lightning routing node forwards payments between channels, earning routing fees by providing liquidity paths across the payment network.
RPC Endpoint
An RPC endpoint is a network URL that applications use to communicate with a blockchain node and submit transactions or query data.
RSK (Rootstock)
A Bitcoin sidechain with Ethereum-compatible smart contracts, secured by merge-mining with Bitcoin miners.
RTGS (Real-Time Gross Settlement)
RTGS is a payment system that settles high-value transactions individually and instantly in central bank money without netting.
RTP Network
The Clearing House's Real-Time Payments network, the first US real-time payment system, enabling instant bank-to-bank transfers.
Rug Pull
A rug pull is a crypto scam where project developers abandon a project and abscond with investor funds after attracting liquidity.
Runes
A UTXO-based fungible token protocol on Bitcoin designed to be more efficient than BRC-20 by using OP_RETURN instead of inscriptions.
Sanctions Screening
The compliance process of checking customers and transactions against government sanctions lists to prevent prohibited financial activity.
Sandwich Attack
An MEV strategy where an attacker front-runs and back-runs a victim's DEX trade, profiting from the price impact they cause.
SAR (Suspicious Activity Report)
A regulatory filing that financial institutions must submit to FinCEN when they detect transactions that may indicate money laundering or fraud.
Satoshi (SAT)
A satoshi is the smallest unit of bitcoin, equal to 0.00000001 BTC, named after Bitcoin's pseudonymous creator.
Satoshi Nakamoto
The pseudonymous creator of Bitcoin who published the original whitepaper and mined the genesis block before disappearing in 2011.
Scheme Fee
The fee charged by card networks (Visa, Mastercard) for using their infrastructure, branding, and dispute resolution systems.
Schnorr Signatures
A digital signature scheme enabled by Taproot that offers smaller signatures, native multisig aggregation, and improved privacy.
Script Path Spend
A script path spend reveals and executes a specific script branch from a Taproot output's hidden script tree to authorize a transaction.
Scriptless Script
Scriptless scripts use Schnorr signature properties to encode smart contract logic in signatures rather than in on-chain Bitcoin Script.
ScriptPubKey (Output Script)
The locking script placed on a Bitcoin transaction output that defines the conditions required to spend those funds.
ScriptSig (Input Script)
The unlocking script provided when spending a Bitcoin output, containing signatures and data that satisfy the output's spending conditions.
secp256k1
The specific elliptic curve used by Bitcoin for all public key cryptography, chosen by Satoshi for its efficiency and security properties.
Secure Element
A tamper-resistant chip that stores cryptographic keys and performs signing operations in hardware wallets and mobile devices, protecting against physical and software attacks.
Secure Remote Commerce (SRC)
An EMVCo framework that standardizes online checkout across card networks with tokenized credentials and consistent user experience.
Security Token
A security token is a blockchain-based digital asset that represents ownership in a real-world asset and is subject to securities regulations.
Seed Phrase
A human-readable list of words (typically 12 or 24) that encodes the master seed for an HD wallet.
Seedless Wallet
A cryptocurrency wallet that eliminates traditional seed phrase backup by using alternative key management like MPC or passkeys.
SegWit (Segregated Witness)
A Bitcoin protocol upgrade that separates signature data from transaction data, fixing malleability and increasing effective block capacity.
Seigniorage
Seigniorage is the profit a currency issuer earns from the difference between the face value of money and its production cost.
Self-Custody
Holding your own private keys rather than trusting a third party, embracing the principle of not your keys, not your coins.
Self-Sovereign Identity (SSI)
Self-sovereign identity gives individuals full ownership and control over their digital identity without relying on centralized authorities or intermediaries.
Selfish Mining
A mining strategy where a miner withholds discovered blocks to gain a disproportionate share of rewards, at the network's expense.
SEPA Transfer
The Single Euro Payments Area enables euro-denominated bank transfers across 36 European countries with standardized rules.
Sequence Number
A per-input field in Bitcoin transactions used for relative timelocks (BIP-68) and signaling Replace-By-Fee (BIP-125).
Sequencer
A sequencer is the entity in a rollup that orders transactions, batches them, and submits results to the base layer for settlement.
Session Key
A session key is a temporary, limited-permission key that lets apps sign transactions on a user's behalf without repeated approvals.
Settlement
The final, irrevocable transfer of value that completes a transaction, often requiring on-chain confirmation.
Settlement Layer
The base blockchain layer where final, irreversible transaction settlement occurs, providing security guarantees for upper layers.
SHA-256
The cryptographic hash function at the core of Bitcoin mining, address generation, and transaction integrity verification.
Shamir's Secret Sharing
A cryptographic scheme that splits a secret into multiple shares, where any k-of-n shares can reconstruct the original secret.
Sharding
Sharding is a database partitioning technique applied to blockchains, splitting the network into parallel segments to increase throughput.
Shared Security
Shared security allows multiple blockchain networks to inherit economic security from a larger base chain rather than bootstrapping their own.
Shared Sequencer
A shared sequencer provides decentralized transaction ordering for multiple rollups, enabling cross-rollup atomic composability.
Shor's Algorithm Vulnerability
A quantum computing threat to elliptic curve cryptography (ECC) that could theoretically break the digital signatures securing Bitcoin and stablecoin transactions.
Side-Channel Attack
A side-channel attack extracts cryptographic secrets by analyzing physical signals like timing, power consumption, or electromagnetic emissions rather than breaking the underlying math.
Sidechain
A separate blockchain pegged to a parent chain, enabling different features or tradeoffs while maintaining asset transferability.
Sighash Flag
A flag in Bitcoin signatures specifying which parts of the transaction the signature commits to, enabling flexible signing schemes.
SIGHASH_ANYPREVOUT (BIP-118)
SIGHASH_ANYPREVOUT is a proposed Bitcoin signature hash flag that allows a signature to apply to any input UTXO, enabling eltoo and better Layer 2 protocols.
Signature Aggregation
Signature aggregation combines multiple cryptographic signatures into a single compact signature, reducing transaction size and fees.
Signing Device
A dedicated hardware device that stores private keys and signs transactions, isolating keys from general-purpose computers.
Silent Payments
A proposed Bitcoin protocol for generating unique addresses from a static public identifier, enabling private donations without interaction.
SIM Swap Attack
A social engineering attack where an attacker convinces a carrier to transfer a victim's phone number, intercepting 2FA codes.
Simple Taproot Channels
Simple Taproot Channels are a Lightning channel type using Taproot outputs for improved privacy and smaller on-chain footprint.
Slashing
A penalty mechanism in proof-of-stake systems that destroys a portion of a validator's staked tokens for protocol violations like double-signing or attesting to conflicting blocks.
Slippage
The difference between the expected price and executed price of a trade, caused by low liquidity or large order size.
Smart Contract
A smart contract is a self-executing program stored on a blockchain that automatically enforces agreement terms when conditions are met.
Smart Contract Audit
A smart contract audit is a systematic security review of blockchain code to identify vulnerabilities before deployment to mainnet.
Smart Wallet
A smart wallet uses programmable logic like account abstraction to enable features such as social recovery and gas sponsorship.
Social Engineering Attack
A manipulation technique that exploits human psychology rather than technical vulnerabilities to steal cryptocurrency or access credentials.
Social Recovery Wallet
A wallet design where trusted guardians can help recover access if the owner loses their key, without guardians having spending power.
Soft Decline
A soft decline is a temporary payment rejection that may succeed if the transaction is retried later or with modified parameters.
Soft Fork
A backward-compatible Bitcoin protocol upgrade where old nodes still accept new blocks, enabling gradual adoption of new rules.
Soft Peg
A soft peg is a flexible exchange rate mechanism that targets a specific price but allows temporary deviations within a band.
SoftPOS (Software Point of Sale)
SoftPOS turns a standard smartphone into a contactless payment terminal using its built-in NFC reader, eliminating the need for dedicated hardware.
Solo Mining
Solo mining is the practice of mining cryptocurrency independently without joining a pool, earning the full block reward if a block is found.
SOPR (Spent Output Profit Ratio)
SOPR measures whether Bitcoin holders are selling at a profit or loss by comparing the price at which coins were spent to the price at which they were acquired.
Soulbound Token (SBT)
A soulbound token is a non-transferable NFT permanently tied to a wallet, used for identity, credentials, and reputation on-chain.
Sound Money
Money with properties like scarcity, durability, and resistance to debasement that make it a reliable store of value over time.
Sovereign Rollup
A rollup that uses the base layer only for data availability, with its own nodes verifying execution independently.
Specified Stablecoins
A regulatory classification in Hong Kong for fiat-referenced stablecoins with official currency ties, subject to mandatory licensing requirements.
SPEI (Sistema de Pagos Electrónicos Interbancarios)
Mexico's electronic interbank payment system providing near-instant peso transfers between bank accounts 24/7.
Splicing
A technique to add or remove funds from a Lightning channel without closing it, maintaining channel uptime and routing capabilities.
Split Payment
A split payment divides a single transaction amount across multiple payment methods, accounts, or recipients simultaneously.
Sponsor Bank
A chartered bank that provides regulatory and banking infrastructure for fintech companies to offer financial services.
Spot ETF
A spot ETF holds the actual underlying asset rather than derivatives, giving investors direct price exposure through traditional brokerage accounts.
Spot Trading
Spot trading is the immediate purchase or sale of a cryptocurrency at the current market price with instant settlement.
SPV Client (Simplified Payment Verification)
A lightweight Bitcoin client that verifies transactions using block headers and Merkle proofs without downloading the full blockchain.
Stablecoin
A stablecoin is a cryptocurrency designed to maintain a stable value, typically pegged 1:1 to a fiat currency like the US dollar.
Stablecoin Arbitrage
Trading strategies that profit from price deviations between a stablecoin's market price and its peg, helping maintain stability.
Stablecoin Blacklist (Freeze Function)
The ability of centralized stablecoin issuers to freeze or blacklist specific addresses, preventing them from transacting.
Stablecoin Payment Rails
Using stablecoins as the settlement layer for payments, enabling instant cross-border transfers at near-zero cost.
Stablecoin Payout
A stablecoin payout uses dollar-pegged tokens to disburse funds globally, settling in minutes instead of the days required by traditional banking rails.
Stablecoin Reserves
The assets backing a stablecoin's value, ranging from cash and Treasuries to crypto collateral and real-world assets.
Stablecoin Risk Assessment
A framework for evaluating stablecoin safety based on reserves, governance, legal structure, and redemption mechanics.
Stablecoin Savings Rate
Interest earned by depositing stablecoins into protocol-native savings contracts, like MakerDAO's DSR or sDAI.
Stablecoin Supply and Market Cap
The total outstanding value of stablecoins in circulation, a key indicator of crypto market liquidity and adoption.
Stablecoin Trilemma
The design tradeoff between decentralization, capital efficiency, and price stability that every stablecoin must navigate.
Stablecoin Yield
Returns earned on stablecoin deposits through lending, liquidity provision, or issuer revenue sharing programs.
Staking
Locking up cryptocurrency as collateral to participate in proof-of-stake consensus, earning rewards for securing the network.
Staking Rewards
Staking rewards are the cryptocurrency earnings validators receive for locking tokens and participating in proof-of-stake consensus.
State Bloat
State bloat is the uncontrolled growth of blockchain state data that increases storage requirements and slows node synchronization.
State Channel
A Layer 2 construct where participants exchange signed state updates off-chain, with on-chain settlement only for disputes.
State Compression
State compression reduces on-chain storage costs by storing only a cryptographic proof on-chain while keeping full data off-chain or in logs.
State Root
A state root is a cryptographic hash that summarizes the entire current state of a blockchain into a single fixed-size value.
Statechain Entity (SE)
The semi-trusted server operator in a statechain protocol that co-signs transactions without having unilateral control over funds.
Statechains
A Layer 2 protocol enabling off-chain transfer of UTXO ownership through co-signing key rotation with a statechain entity.
Static Channel Backup (SCB)
A backup file containing the information needed to recover Lightning channel funds by triggering force-closes with channel partners.
Stealth Address
A stealth address is a one-time address generated by the sender so that each payment to the same recipient uses a unique on-chain address.
Stock-to-Flow Model
The stock-to-flow model measures Bitcoin's scarcity by dividing existing supply (stock) by annual production rate (flow).
Stop-Loss Order
A stop-loss order automatically sells a cryptocurrency when its price drops to a specified level, limiting potential losses.
Store of Value
A store of value is an asset that maintains its purchasing power over time, often cited as a primary use case for Bitcoin and gold.
Stored Value
Prepaid funds loaded onto a card, account, or digital wallet that can be spent until depleted, like gift cards or transit cards.
Strategic Bitcoin Reserve
Learn what a strategic bitcoin reserve is: a government or institutional stockpile of bitcoin held as a long-term reserve asset.
Stratum Protocol
The communication protocol between Bitcoin miners and mining pools, with Stratum V2 adding encryption and decentralized block templates.
Strong Customer Authentication (SCA)
A European regulation requiring two-factor verification for electronic payments, reshaping online checkout experiences across the EU.
Submarine Swap
An atomic exchange between on-chain Bitcoin and Lightning payments, enabling trustless movement of funds between layers.
Supply Chain Attack (Hardware Wallets)
Tampering with hardware wallets during manufacturing or shipping to extract private keys or install malicious firmware.
Supply Shock
A supply shock occurs when a sudden change in available supply disrupts market equilibrium, causing rapid price movement.
SWIFT Network
The global messaging network connecting 11,000+ banks to coordinate cross-border payments and financial communications.
Sybil Attack
An attack where a single adversary creates many fake identities to gain disproportionate influence over a network.
Synthetic Asset
A token that tracks the price of an external asset through oracles and collateralization rather than direct backing.
Taint Analysis
Tracking the flow of Bitcoin from known-bad addresses through subsequent transactions to identify contaminated funds.
Tap to Pay
Tap to pay is a contactless payment method using NFC technology that lets customers pay by tapping their card or phone near a payment terminal.
Taproot
A Bitcoin upgrade activating Schnorr signatures, MAST, and Tapscript for improved privacy, efficiency, and smart contract capabilities.
Taproot Assets (TAP)
Learn what Taproot Assets is: a Bitcoin protocol for issuing stablecoins, tokens, and NFTs on-chain using Taproot transactions.
Tapscript
Tapscript is the upgraded scripting language used inside Taproot script-path spends, enabling new opcodes and improved flexibility.
Taptree
A taptree is the Merkle tree of spending conditions embedded in a Taproot output, allowing complex scripts while preserving privacy.
Thiers' Law
The inverse of Gresham's Law: when people can freely choose their money, good money drives out bad money from circulation.
Threshold Signature
A cryptographic scheme where t-of-n parties must cooperate to produce a valid signature, without any party holding the complete key.
Time Preference
An economic concept measuring the degree to which people prefer present goods over future goods, central to Bitcoin's savings thesis.
Time to Finality
Time to finality measures how long it takes for a blockchain transaction to become irreversible and permanently settled.
Time-Bandit Attack
A theoretical attack where miners with sufficient hashrate reorg past blocks to steal high-value transactions or manipulate history.
Timelock
A Bitcoin script condition that prevents spending until a specified block height or timestamp is reached.
Token
A token is a digital asset created on an existing blockchain, representing value, utility, governance rights, or real-world assets.
Token Approval
A token approval is an on-chain permission that lets a smart contract spend a specified amount of tokens from your wallet.
Token Bridge
Infrastructure that transfers tokens between different blockchains by locking on one chain and minting a representation on another.
Token Burn
A token burn permanently removes cryptocurrency tokens from circulation by sending them to an unspendable address, reducing total supply.
Token Gating
Token gating restricts access to content, communities, or features based on ownership of a specific token or NFT in the user's wallet.
Token Migration
Token migration is the process of moving a cryptocurrency token from one blockchain or contract to another, often due to protocol upgrades.
Token Sale (ICO)
A token sale is a fundraising event where a project sells newly created cryptocurrency tokens to early investors, also known as an ICO.
Token Standard
A specification defining how tokens are created, transferred, and managed on a blockchain platform.
Token Swap
A token swap is the exchange of one cryptocurrency for another, executed either on a centralized exchange or through a DeFi protocol.
Token Unlock
A token unlock is a scheduled event where previously locked or vested tokens become available for trading, often causing price volatility.
Token Vesting
A schedule that gradually releases tokens to team members, investors, or contributors over time, preventing immediate market dumps.
Tokenization (Payments)
Replacing sensitive card numbers with non-sensitive tokens to reduce fraud risk and PCI compliance burden.
Tokenized Deposit
A tokenized deposit is a bank deposit represented as a blockchain token, combining banking regulatory protections with programmable on-chain settlement.
Tokenized Treasury
US Treasury bonds or bills represented as blockchain tokens, enabling on-chain access to government debt yield.
Tokenomics
Tokenomics refers to the economic design of a cryptocurrency token, including supply, distribution, utility, and incentive mechanisms.
Tor and Bitcoin
Using the Tor anonymity network to hide a Bitcoin node's IP address, improving privacy but introducing potential attack vectors.
Total Supply
Total supply is the number of cryptocurrency tokens that currently exist, including locked or reserved tokens but excluding permanently burned ones.
Trading Pair
A trading pair represents two assets that can be exchanged for each other on a crypto exchange, like BTC/USD or ETH/BTC.
Trading Volume
The total value or number of cryptocurrency units exchanged within a given period, indicating market liquidity and activity.
Trampoline Payments
A Lightning Network routing technique where lightweight clients delegate pathfinding to intermediate nodes, enabling mobile wallets to send payments without maintaining full network state.
Transaction Batching
Transaction batching combines multiple Bitcoin payments into a single on-chain transaction, reducing fees and block space usage.
Transaction Graph
The directed acyclic graph formed by all Bitcoin transactions, where outputs from one transaction become inputs to the next.
Transaction ID (txid)
A unique 256-bit hash identifying a Bitcoin transaction, computed from the serialized transaction data.
Transaction Malleability
The ability to modify a Bitcoin transaction's ID without invalidating it, a critical bug that SegWit fixed to enable Lightning.
Transaction Monitoring
Automated surveillance of financial transactions to detect suspicious patterns indicating money laundering, fraud, or sanctions violations.
Transaction Pinning
Transaction pinning is a mempool attack where an adversary prevents a legitimate transaction from being fee-bumped or confirmed.
Transaction Simulation
A security feature that previews the outcome of a blockchain transaction before signing, showing expected token transfers and approvals.
Transaction Throughput
Transaction throughput measures the number of transactions a blockchain network can process per second, a key metric for scalability.
Transfer Restriction
Smart contract rules that limit who can send or receive a token, used for compliance in regulated stablecoins and securities.
Travel Rule
The travel rule requires financial institutions to share sender and recipient identity information for transfers above a certain threshold.
Trusted Execution Environment (TEE)
An isolated processing environment within a CPU that protects code and data from the main operating system and other applications.
Trusted Setup
A trusted setup is a one-time ceremony that generates cryptographic parameters for zero-knowledge proof systems, requiring honest participation.
Trustless
Systems that operate through cryptographic verification rather than relying on trusted third parties.
Trustless Bridge
A cross-chain bridge that verifies transactions cryptographically without relying on trusted intermediaries or multisig committees.
TUSD (TrueUSD)
A fiat-backed stablecoin with real-time attestations of reserves, which faced controversy over its reserve management practices.
TVL (Total Value Locked)
The total value of crypto assets deposited in a DeFi protocol, the most common (but imperfect) metric for DeFi adoption.
TWAP (Time-Weighted Average Price)
TWAP is a pricing algorithm that calculates an asset's average price over a specific time window to reduce manipulation risk.
Unbanked
The unbanked are people without access to traditional banking, a key demographic for mobile-first crypto payment solutions.
Uncle Block (Ommer)
An uncle block is a valid block that was mined but not included in the canonical chain, receiving a partial reward in some blockchain protocols.
Unconfirmed Transaction
An unconfirmed transaction is a Bitcoin transaction broadcast to the network but not yet included in a mined block.
Unit of Account
A unit of account is a standard measurement of value that allows goods, services, and debts to be priced and compared consistently.
UPI (Unified Payments Interface)
India's real-time mobile payment system processing billions of transactions monthly through interoperable bank-linked apps.
USDB Stablecoin
A Bitcoin-native stablecoin built on Spark that pays yield to holders, issued by Flashnet and backed by dollar-denominated reserves.
USDC (USD Coin)
A regulated dollar-backed stablecoin issued by Circle, fully reserved with cash and US Treasuries, available on multiple blockchains.
USDP (Pax Dollar)
A regulated dollar stablecoin issued by Paxos Trust Company, backed by cash and US Treasuries under New York banking supervision.
USDT (Tether)
The largest stablecoin by market cap, issued by Tether Limited, widely used in trading and emerging market payments.
UST Collapse (Terra/Luna)
The catastrophic failure of Terra's algorithmic stablecoin in May 2022, wiping out $40B+ and triggering industry-wide contagion.
Utility Token
A utility token provides access to a product or service within a blockchain ecosystem rather than representing ownership or investment returns.
Utreexo
Utreexo is a hash-based accumulator that compresses the Bitcoin UTXO set into a compact cryptographic proof, reducing node storage needs.
UTXO (Unspent Transaction Output)
The fundamental unit of Bitcoin ownership, representing an unspent output from a previous transaction that can be used as input to a new transaction.
UTXO Consolidation
Combining many small UTXOs into fewer larger ones during low-fee periods to reduce future transaction costs.
UTXO Set
The complete collection of all unspent transaction outputs on Bitcoin, representing the current state of who owns what.
V3 Transaction (TRUC)
V3 transactions are a Bitcoin mempool policy using Topologically Restricted Until Confirmation rules to prevent transaction pinning.
Validator Economics
Validator economics covers the costs, revenues, and incentive structures that determine the profitability of running a blockchain validator.
Validator Node
A validator node is a computer that participates in proof-of-stake consensus by proposing and attesting to new blocks in exchange for staking rewards.
Validator Set
The group of nodes authorized to participate in block production and consensus in a proof-of-stake or permissioned blockchain network.
Validity Proof
A cryptographic proof submitted to the base layer that proves a batch of L2 transactions was executed correctly, enabling ZK rollups.
Validium
A Layer 2 design using validity proofs like ZK rollups but storing data off-chain, trading security for lower costs.
Vanity Address
A vanity address is a Bitcoin address containing a custom pattern or word, generated by repeatedly creating key pairs until a match is found.
Variable Recurring Payment (VRP)
A variable recurring payment is an open banking payment type where merchants collect varying amounts on a flexible schedule with consent.
VASP (Virtual Asset Service Provider)
A VASP is any business that facilitates virtual asset transactions, including exchanges, custodians, and transfer services, subject to AML/KYC regulations.
Velocity Check
A fraud detection rule that flags or blocks transactions when a user exceeds a threshold of attempts within a time window.
Verifiable Computation
Verifiable computation allows one party to prove a computation was executed correctly without the verifier re-executing it.
Verifiable Credential (VC)
A verifiable credential is a tamper-proof digital attestation that can be cryptographically verified without contacting the original issuer.
Verifiable Random Function (VRF)
A verifiable random function produces a pseudorandom output with a proof that anyone can verify, enabling fair and tamper-proof on-chain randomness.
Verkle Tree
A Verkle tree is an advanced data structure that reduces proof sizes compared to Merkle trees, planned for Ethereum to enable stateless clients.
Virtual Bytes (vBytes)
The weight-adjusted size metric for Bitcoin transactions, determining fees under the SegWit weight system.
Virtual Card
A digitally-generated payment card number used for online or in-app transactions without requiring a physical plastic card.
Void Transaction
A void transaction cancels an authorized payment before it settles, releasing the held funds back to the cardholder without a refund process.
Vote Escrow (veToken)
Vote escrow is a DeFi governance model where users lock tokens for a fixed period to gain voting power and boosted rewards.
VTXO (Virtual Transaction Output)
An off-chain representation of Bitcoin ownership used in protocols like Ark that can be settled on-chain when needed.
Wallet (Cryptocurrency)
A cryptocurrency wallet is software or hardware that stores private keys and enables users to send, receive, and manage digital assets.
Wallet Fingerprinting
Identifying which wallet software created a Bitcoin transaction by analyzing patterns like input ordering and script types used.
WalletConnect
WalletConnect is an open protocol that connects cryptocurrency wallets to decentralized applications via QR code or deep link pairing.
Warm Wallet
A warm wallet is a cryptocurrency wallet that stays online but uses additional security controls to balance accessibility with protection.
Watch-Only Wallet
A wallet that can view balances and generate addresses but cannot sign transactions, used for monitoring without key exposure.
Watchtower
An outsourced monitoring service that watches for channel breaches on the Lightning Network and broadcasts penalty transactions to protect users who are offline.
Web3
Web3 describes a vision for a decentralized internet built on blockchain technology, where users own their data, assets, and digital identities.
Wei
The smallest denomination of Ether, where one ETH equals 10^18 wei, named after cryptographer Wei Dai.
Weight Units (WU)
Weight units are the SegWit measurement system for Bitcoin transaction size, with blocks limited to 4 million WU.
Whale
A whale is an individual or entity holding a large amount of cryptocurrency, capable of influencing market prices through their trades.
Whitelist (Allowlist)
A whitelist is a pre-approved list of addresses, users, or entities granted access to a specific blockchain operation or event.
Whitepaper
A whitepaper is a technical document describing the design, purpose, and mechanics of a blockchain protocol or cryptocurrency project.
Whole-Coiner
A person who owns at least one full Bitcoin, a milestone of increasing significance as Bitcoin's price rises over time.
Wire Transfer
An electronic funds transfer between banks that settles individually and typically same-day, used for large or urgent payments.
Witness Data
The segregated signature and script data in SegWit transactions, stored separately from the main transaction structure.
Witness Discount
The witness discount is a SegWit feature that counts witness data at one-quarter weight, incentivizing use of Taproot and other witness-based spending.
Witness Version
A version byte in SegWit outputs that determines which script validation rules apply, enabling future Bitcoin protocol upgrades.
Wrapped Asset
A token on one blockchain that represents an asset from another chain, typically held by a custodian or smart contract.
Wrapped Bitcoin (WBTC)
An ERC-20 token on Ethereum backed 1:1 by Bitcoin held in custody, enabling Bitcoin to participate in Ethereum DeFi.
Wumbo Channel
A Lightning channel exceeding the default 0.1677 BTC capacity limit, enabled by both peers advertising wumbo feature support.
Yield Aggregator
A DeFi protocol that automatically moves funds between yield opportunities to maximize returns for depositors.
Yield Curve
A yield curve plots interest rates across different loan maturities, revealing market expectations about future rates and risk.
Yield Farming
The practice of moving crypto between DeFi protocols to maximize returns from trading fees, token incentives, and interest.
Yield Tokenization
Yield tokenization splits a yield-bearing asset into separate principal and yield components that can be traded independently on-chain.
Yield-Bearing Stablecoin
A yield-bearing stablecoin automatically accrues interest to holders, typically backed by Treasury bills or DeFi lending revenue.
Zero-Conf Channels
Lightning channels that can be used immediately before the funding transaction confirms on-chain, accepting temporary trust tradeoffs.
Zero-Knowledge Proof (ZKP)
A cryptographic method allowing one party to prove they know something without revealing the underlying information.
ZK Rollup
A Layer 2 scaling solution that uses zero-knowledge proofs to verify off-chain computation, enabling instant finality withdrawals.
zk-SNARK
Zero-Knowledge Succinct Non-Interactive Argument of Knowledge: compact proofs verifiable in milliseconds without interaction.
zk-STARK
Zero-Knowledge Scalable Transparent Argument of Knowledge: post-quantum proofs with no trusted setup but larger proof sizes.
zkEVM (Zero-Knowledge Ethereum Virtual Machine)
A zkEVM is a virtual machine compatible with Ethereum that generates zero-knowledge proofs to verify transaction execution off-chain.