Crypto glossary

Short, accurate definitions of the words you meet in wallets, explorers and our tools. Open a term for its whole definition, related terms and the tool that goes with it. For the bigger picture, read the guides.

170 terms · showing 5

51% attack: An attempt by someone controlling most of a proof-of-work network’s hash rate to rewrite recent history, for example to double-spend their own coins.

Account abstractionalso ERC-4337: A way to make a wallet behave more like a smart contract, so it can batch actions, let someone else pay gas or recover access with custom rules.
Address: A string, derived from a public key or a script, that can receive funds.
Address clustering: Grouping addresses that are probably controlled by the same wallet, for example because they were spent together in one Bitcoin transaction.
Address poisoning: A scam that plants a look-alike address (matching the first and last characters of one you use) in your transaction history, hoping you copy it by mistake.
Admin key: An address with special powers over a smart contract, such as upgrading its code, pausing it or minting tokens.
Airdrop: A distribution of free tokens to many addresses, usually to reward early users or spread ownership.
All-time highalso ATH: The highest price an asset has ever traded at, usually measured in US dollars.
Altcoin: Any cryptocurrency other than Bitcoin.
Anti-money launderingalso AML: The laws and controls that stop criminal proceeds entering the legitimate financial system.
APR and APY: Annual percentage rate is a simple yearly rate; annual percentage yield includes compounding.
Arbitrage: Buying an asset in one market and selling it in another to capture a price gap.
Atomic swap: A trade of coins across two blockchains that either completes on both sides or fails on both, usually with hashed timelock contracts.
Automated market makeralso AMM: A decentralised exchange design in which a pool of two tokens sets the price from the ratio of its balances, instead of matching buyers with sellers.

Base fee: On Ethereum and most EVM chains, the protocol-set part of the gas price.
Bear market: A long stretch in which prices trend down and sentiment stays weak.
Bech32 and Bech32m: The address formats for native SegWit (bc1q…, BIP 173) and Taproot (bc1p…, BIP 350).
BIPalso Bitcoin Improvement Proposal: A document describing a change or standard for Bitcoin, such as BIP 39 for seed phrases or BIP 125 for replace-by-fee.
BIP 21 payment link: A standard for Bitcoin payment requests: a link beginning “bitcoin:” followed by the address, with an optional amount, label and message, usually shown as a QR code.
Bitcoin dominance: Bitcoin’s share of the total market capitalisation of all cryptocurrencies.
Block: A batch of transactions added to a blockchain at once. Bitcoin blocks arrive about every ten minutes on average; Ethereum uses 12-second slots, though a slot need not contain a block.
Block explorer: A website that shows the contents of a blockchain: blocks, transactions, addresses and balances.
Block height: The number of blocks before a given block in the chain. The first Bitcoin block has height 0.
Block subsidy: The new coins a Bitcoin miner may create in each block, on top of the fees.
Blockchain: A shared ledger of transactions grouped into blocks, each of which contains the hash of the block before it, so changing an old entry breaks every later link.
Bridge: A system that moves assets between blockchains, usually by locking them on one chain and issuing a representation on the other.
Bull market: A long stretch in which prices trend up and sentiment stays strong.

Calldataalso input data, function selector: The input data of an EVM transaction. For a contract call, its first four bytes are the function selector, taken from a hash of the function’s name and argument types, and the rest encodes the arguments.
Candlestick: A price bar showing the open, high, low and close for a period such as one hour or one day.
Centralised exchangealso CEX: A company that holds customers’ funds and matches their trades.
Change output: The part of a Bitcoin payment sent back to the payer, because a transaction spends whole unspent outputs and returns what is left over.
Child pays for parentalso CPFP: Speeding up an unconfirmed Bitcoin transaction by spending one of its outputs in a new transaction with a high fee, so miners include both to collect it.
Circulating supply: The number of coins publicly available and moving, as estimated by data providers.
CoinJoin: A Bitcoin transaction in which many people combine their inputs and receive equal-sized outputs, so observers cannot tell whose coins went where.
Cold storage: Keeping private keys on a device or medium that never connects to the internet, such as a hardware wallet or an offline paper backup.
Collateral: Assets pledged to secure a loan or leveraged position. If their value falls too far or the borrower breaks the rules, part or all of the collateral can be liquidated.
Confirmation: Each block added on top of the block that contains a transaction.
Consensus: The rules every node enforces, and the process by which a network agrees on a single history of transactions.
Cost basis: What an asset cost you, including fees, which is subtracted from the proceeds of a sale to work out the gain or loss for tax.
Cross-chain: Moving assets or messages between different blockchains. Cross-chain systems usually rely on a bridge or a special validator set, so the risk is not just the two chains but the extra system in between.
Cryptocurrency: A digital asset recorded on a blockchain and moved by signing transactions with a private key, with no bank or company keeping the ledger.
Custodial and non-custodial: A custodial service holds the keys to your crypto for you; with a non-custodial wallet only you hold them.
Custodian: A company that holds crypto on behalf of customers and controls the private keys.

DAOalso decentralised autonomous organisation: A group that manages a treasury or protocol through on-chain voting and smart contracts, often with a multisig carrying out its decisions.
dAppalso decentralised application: A decentralised application: software that uses a smart contract or blockchain as part of how it works, usually through a wallet in the browser.
Decentralised exchangealso DEX: A smart contract where people swap tokens directly from their own wallets.
DeFialso decentralised finance: Lending, trading and other financial services run by smart contracts rather than by companies.
Delegatecall: An EVM operation that runs another contract’s code with the calling contract’s own storage and authority.
Delisting: Removing a coin, token or trading pair from an exchange. After a delisting, liquidity often worsens and users may have a deadline to withdraw or sell.
Depeg: When a stablecoin trades noticeably away from the value it is meant to hold, usually because holders doubt they can redeem it in full.
Deposit address: The address an exchange or service gives you so it can credit your account when funds arrive.
Derivation path: The route from a wallet's master key to one particular key, written like m/84'/0'/0'/0/0.
Derivatives: Contracts whose value comes from an underlying asset rather than from spot ownership of the asset itself.
Difficulty adjustment: Every 2,016 blocks (about two weeks) Bitcoin resets how hard it is to find a block, so blocks keep arriving about every ten minutes however much mining power joins or leaves.
Dollar-cost averagingalso DCA: Investing a fixed amount on a regular schedule, whatever the price.
Double spend: Spending the same coins twice by getting one payment accepted and later invalidating it with a competing chain or transaction.
Dust: An output so small that spending it would cost more in fees than it is worth.

EIP-1559: The 2021 change to Ethereum fees that introduced a protocol-set base fee, burned in every block, plus an optional tip for validators.
EIP-4844also blobs: The March 2024 Ethereum upgrade known as proto-danksharding.
EIP-7702: Part of Ethereum’s May 2025 Pectra upgrade. It lets a key-controlled account delegate its behaviour to smart-contract code, enabling batching or sponsored gas without replacing the account itself.
ENSalso Ethereum Name Service: Human-readable names such as example.eth that resolve to addresses.
ERC-1155: An EVM token standard that lets one contract manage many token types, including both fungible and non-fungible items.
ERC-20: The standard interface for fungible tokens on EVM chains, used by most stablecoins and tokens.
ERC-721: The common EVM standard for NFTs in which each token ID is distinct.
Etheralso ETH: The native currency of Ethereum, used to pay for gas and to stake.
Ethereum Virtual Machinealso EVM: The environment that runs smart contracts on Ethereum. Chains that use it, such as BNB Smart Chain, Polygon PoS and Ethereum’s layer 2s, share the same address format and tools.
Event log: A record a smart contract emits while it runs, such as a token’s Transfer(from, to, amount).
Extended public keyalso xpub, ypub, zpub: A key from which a wallet’s whole series of addresses can be derived.
Externally owned accountalso EOA: An EVM account controlled by a private key rather than by its own permanent contract code.

Faucet: A service that gives out tiny amounts of testnet coins for development or practice.
Fear & Greed Index: A daily 0–100 sentiment score for the crypto market published by alternative.me.
Fee ratealso sat/vB: The price of Bitcoin block space: a transaction’s fee in satoshis divided by its size in virtual bytes.
Finality: The point after which a block cannot be reversed.
Flash loan: A loan from a smart contract that must be borrowed and repaid within the same transaction, otherwise the whole transaction reverts.
Fork: A change to a blockchain’s rules.
Front-running: Getting a transaction in first after seeing another one waiting in the mempool, usually by paying a higher fee.
Fully diluted valuationalso FDV: The price multiplied by the maximum supply, or by the total supply on sites that use that shortcut.
Funding rate: The periodic payment exchanged between long and short positions in a perpetual swap to keep its price close to the spot market.
Futures: A contract to buy or sell an asset at a future date, or to settle the price difference without delivering the asset.

Gas: The unit that measures computation on EVM chains. A plain ETH transfer uses 21,000 gas; you pay gas used × (base fee + priority fee).
Genesis block: The first block in a blockchain. It anchors the chain’s history, and every later block height is counted from it.
Governance token: A token used to vote on changes to a protocol, treasury or fee settings.
Gwei: One billionth of an ether (0.000000001 ETH), the usual unit for gas prices.

Halving: The event every 210,000 blocks (roughly four years) when Bitcoin’s block subsidy halves.
Hardware wallet: A small device that keeps private keys offline and signs transactions inside itself, showing the details on its own screen for you to confirm.
Hash: The short, fixed-length fingerprint a hash function produces from any data.
Hash rate: The total computing power miners devote to a proof-of-work network, in hashes per second.
HD walletalso hierarchical deterministic wallet: A wallet (BIP 32) that derives an unlimited tree of keys and addresses from one seed, so a single backup covers them all.
Honeypot token: A token whose contract lets people buy it but stops them selling, so its price only appears to rise.
Hot wallet: A wallet whose keys live on an internet-connected device. Convenient for spending, and more exposed than cold storage.

Impermanent loss: The shortfall a liquidity provider suffers compared with simply holding the two tokens, because the pool sells the one that rises and buys the one that falls.
Initial coin offeringalso ICO: A fundraising sale in which a project sells new tokens before or around launch, usually in exchange for established crypto or cash.

Know your customeralso KYC: The identity checks a regulated business carries out on its customers.
Know your transactionalso KYT: Screening and monitoring transactions (for example checking deposit and withdrawal addresses against sanctions lists and risk labels) rather than only the customer.

Layer 2: A network that processes transactions separately and relies on a base chain for security.
Leverage: Borrowing or using margin so a small amount of capital controls a larger position.
Lightning Network: A Bitcoin layer 2 made of payment channels that settles instant, low-fee payments off-chain.
Limit order: An instruction to buy or sell only at your chosen price or better.
Liquid staking: Staking through a protocol that gives you a token representing your staked coins, such as stETH for staked ether, which can be traded or used elsewhere.
Liquidation: The forced closing of a leveraged position or loan when its collateral falls below the required level.
Liquidity: How easily an asset can be bought or sold without moving its price.
Liquidity pool: A pot of tokens locked in a decentralised exchange or lending protocol for others to trade against or borrow from.
Long and short: To go long is to profit if the price rises; to go short is to profit if it falls.

Market capitalisationalso market cap: Price multiplied by circulating supply. The usual way to rank coins by size.
Market order: An instruction to trade immediately at the best available prices in the order book or pool.
Maximum supply: The most coins that can ever exist under a protocol’s rules.
Memecoin: A token whose appeal comes mainly from internet culture, jokes or community attention rather than from a product or cash flow.
Mempool: The set of valid, unconfirmed transactions a node holds and relays.
Merkle tree: A tree of hashes that lets a large set of data be verified from a short proof instead of from the whole set.
MEValso maximal extractable value, miner extractable value: Extra profit a block producer or searcher can make by ordering, inserting or excluding transactions.
Mining: Using computing power to find valid proof-of-work blocks, in return for the block subsidy and fees.
Mining pool: A group of miners that combine their hash rate and share the rewards, smoothing out the luck of finding blocks.
Mixer: A service that pools and redistributes coins to hide where they came from.
Multisig: A wallet that needs signatures from several keys (for example 2 of 3) to move funds, so no single lost or stolen key is enough.

NFTalso non-fungible token: A unique token, usually representing ownership of a digital item.
Node: Software that checks a blockchain’s rules and relays transactions and blocks.
Nonce: A number used once. On EVM chains it counts an account’s transactions so each runs once and in order; a Safe keeps its own nonce for its transactions.

OFAC and the SDN list: The US Treasury’s Office of Foreign Assets Control and its Specially Designated Nationals list, which has included crypto addresses since 2018.
Oracle: A service that brings outside data, such as prices, onto a blockchain for smart contracts to use.
Order book: The list of open buy and sell orders on an exchange, grouped by price.
Output descriptoralso wallet descriptor: A line of text that says exactly which addresses a Bitcoin wallet uses: the script type, the extended public keys and, for multisig, the threshold.

Paper wallet: A private key and address printed on paper. No longer recommended: the key can leak when it is generated or printed, and spending from it means importing the key into software.
Passphrase (BIP 39)also 25th word: An optional extra word or phrase added to a seed phrase. Each passphrase opens a different wallet from the same words, and a forgotten passphrase cannot be recovered.
PayJoin: A Bitcoin payment in which the recipient adds one of its own inputs, so the transaction looks ordinary but breaks the assumption that all its inputs share an owner.
Peel chain: A pattern in which a large sum passes through a series of fresh addresses, splitting off a small payment at each hop.
Permit signaturealso EIP-2612, Permit2: An off-chain signature that grants a token allowance without a transaction.
Perpetual swap: A derivative like a futures contract but with no expiry date.
Phishing: Tricking someone into revealing credentials, seed phrases or one-time codes, or into opening a fake site that asks for a harmful signature.
Priority feealso tip: The tip an EVM transaction pays on top of the base fee; it goes to the validator that includes the transaction.
Private key: The secret number that authorises spending from an address. Anyone who has it controls the funds.
Proof of reserves: Evidence published by an exchange that it holds the customer assets it owes, often with a way to check that your own balance is included.
Proof of stake: A consensus method in which validators lock up coins as collateral to propose and attest to blocks, and lose part of it for misbehaving.
Proof of work: A consensus method in which miners compete to find a block hash below a target by brute-force computation.
Proxy contract: A contract that forwards calls to a separate implementation contract, so the code can be upgraded while the address and funds stay the same.
PSBTalso partially signed Bitcoin transaction: A standard format (BIP 174) for passing an unsigned or partly signed transaction between wallets and signers.
Public key: The key derived from a private key that others may see; addresses are derived from it.

Replace-by-feealso RBF: Replacing an unconfirmed Bitcoin transaction with a new version that pays a higher fee (BIP 125).
Risk score: A summary of how exposed an address is to sanctioned, illicit or high-risk activity, built from labels and transaction patterns.
Rollup: A layer 2 that executes transactions off the Ethereum base chain and posts compressed data back to it for settlement.
Rug pull: A scam in which a project’s creators take investors’ money (by draining liquidity, minting tokens or blocking sales) and disappear.

Safealso Gnosis Safe: A widely used multisig smart-contract wallet on EVM chains. A transaction executes once enough owners sign a hash of its exact contents.
Sandwich attack: A form of MEV in which a searcher places one trade before yours and another after it to move the price against you and capture the difference.
Satoshialso sat: The smallest unit of bitcoin: 0.00000001 BTC. One bitcoin is 100 million sats.
Seed phrasealso recovery phrase: The 12 or 24 words (BIP 39) from which a wallet derives all its keys.
SegWitalso Segregated Witness: The 2017 Bitcoin upgrade that moved signature data into a discounted “witness” section, fixing transaction malleability and lowering fees.
Self-custody: Holding your own keys rather than leaving crypto with an exchange or custodian.
Shamir backupalso SLIP-39: A way of splitting a wallet’s secret into shares so that a set number of them, for example any 2 of 3, restores the wallet, while fewer reveal nothing.
Sidechain: A separate blockchain linked to another chain by a bridge, often with its own validators and security model.
SIM swap: A fraud in which an attacker convinces a mobile carrier to move your phone number to their SIM.
Slippage: The difference between the price you expect and the price you get when a trade executes, usually because the price moved or liquidity was thin.
Smart contract: A program stored on a blockchain that runs exactly as written when called.
Spread: The gap between the price at which you can buy and the price at which you can sell.
Stablecoin: A token designed to track a currency, usually the US dollar.
Staking: Locking up coins to help secure a proof-of-stake network in return for rewards.

Taproot: The November 2021 Bitcoin upgrade that added Schnorr signatures and more flexible scripts.
Testnet: A blockchain used for testing, with coins that have no real market value.
Timelock: A delay enforced by code. In smart contracts it makes changes wait (for example 48 hours) before they can execute; in Bitcoin it stops coins being spent before a given block height or time.
Token approvalalso allowance: Permission you give a contract to move up to a set amount of a token from your wallet.
Token burn: Removing tokens from circulation, usually by sending them to an address no one can spend from or by destroying them in contract logic.
Tokenomics: The design of a token’s supply, issuance, unlocks, incentives and uses inside a project.
Total value lockedalso TVL: The total dollar value of assets deposited in a protocol’s smart contracts.
Trading volume: The value of a coin traded over a period, usually the last 24 hours.
Transaction IDalso txid: The unique hash that identifies a transaction. Paste it into an explorer, or into our accelerator, to see its status.

UTXOalso unspent transaction output: A discrete piece of bitcoin that can be spent. A Bitcoin balance is the sum of an address’s UTXOs, and a payment spends whole UTXOs and returns change.

Validator: A participant in a proof-of-stake network that proposes or attests to blocks after locking up stake.
Virtual bytesalso vB: Bitcoin’s measure of transaction size for fees: the transaction’s weight divided by four.
Volatility: How much and how quickly a price moves. Crypto assets are typically far more volatile than major currencies or stock indices.

Wallet: Software or hardware that stores keys and creates transactions.
Whale: An address or entity holding a very large amount of a coin, whose moves can shift the market.
Wrapped token: A token on one chain that represents an asset locked elsewhere, such as bitcoin held by a custodian or tokens locked in a bridge.

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