Crypto glossary
115 crypto words explained in a sentence or two, each linked to related terms and a fuller guide.
%
51% attack
When one group controls more than half of a network's mining power or stake and can rewrite recent transactions.
Related: Proof of work, Double spend · Read more →
A
Account abstraction
Making a crypto account a programmable smart contract, so it can use passkeys, spending limits, recovery and gas paid by someone else.
Related: Smart contract, Wallet · Read more →
Address
A string of letters and numbers where crypto can be sent, like an account number. It's made from your public key and is safe to share.
Related: Public key, Private key, Wallet · Read more →
Airdrop
Free tokens sent to many wallets, often to promote a project. Real ones exist, but fake 'claim your airdrop' sites are a common way to steal crypto.
Related: Wallet drainer, Phishing · Read more →
AML / KYC
Anti-money-laundering and know-your-customer rules. They're why regulated exchanges ask for your ID.
Related: Exchange · Read more →
Approval
Permission you sign in your wallet that lets a smart contract move some of your tokens. Malicious approvals can empty a wallet, so only approve sites you trust.
Related: Smart contract, Wallet drainer · Read more →
ASIC
A computer chip built for one job. Bitcoin mining is done almost entirely with ASIC machines.
Related: Mining, Proof of work · Read more →
B
Base fee
On Ethereum, the minimum price per unit of gas for the next block, set by the network and burned.
Related: Gas, Gwei, Burn · Read more →
Bitcoin (BTC)
The first cryptocurrency, launched in 2009, with a maximum supply of 21 million coins.
Related: Satoshi, Halving, Proof of work · Read more →
Bitcoin ATM
A kiosk that turns cash into bitcoin. Legitimate, but heavily used in scams; no real bank or agency will ever tell you to use one.
Related: Scam · Read more →
Blob
A chunk of about 128 KB of data that rollups attach to Ethereum blocks since March 2024. Blobs have their own fee and are deleted after about 18 days.
Related: Rollup, Layer 2 · Read more →
Block
A batch of transactions added to a blockchain together.
Related: Blockchain, Hash, Confirmation · Read more →
Block explorer
A website that lets anyone look up transactions, addresses and blocks on a blockchain.
Related: Address · Read more →
Block reward
New coins paid to the miner or validator who adds a block. On Bitcoin it's 3.125 BTC per block since April 2024.
Related: Halving, Mining · Read more →
Blockchain
A shared record of transactions, grouped into blocks that each contain the fingerprint (hash) of the block before.
Related: Block, Hash, Node · Read more →
Bridge
A service that moves tokens from one blockchain network to another. Bridges have been frequent targets of large hacks.
Related: Layer 2 · Read more →
BTC
The ticker symbol and standard abbreviation for bitcoin, taken from the letters of the name (BiTCoin), like a stock ticker. It isn't short for longer words. Some platforms write XBT instead.
Related: Bitcoin (BTC), Satoshi · Read more →
C
Capital gain
Profit from selling an asset for more than its cost basis. In the US, crypto gains are taxed as capital gains.
Related: Cost basis · Read more →
CBDC
Central bank digital currency: digital money issued by a country's central bank. It isn't a decentralized cryptocurrency.
Related: Stablecoin · Read more →
Coin vs. token
A coin is native to its own blockchain (BTC, ETH); a token is built on top of one (USDC on Ethereum).
Related: Token · Read more →
Cold wallet
A wallet whose private keys are kept offline, such as a hardware wallet.
Related: Hardware wallet, Hot wallet · Read more →
Confirmation
A count of how many blocks have been added since your transaction was included. More confirmations mean it's more firmly settled.
Related: Block, Mempool · Read more →
Consensus mechanism
The rules a network uses to agree on which transactions and blocks are valid.
Related: Proof of work, Proof of stake · Read more →
Cost basis
What you paid for an asset, including fees. Used to work out your gain or loss for taxes.
Related: Capital gain · Read more →
Custodial
When a company holds your crypto's private keys for you, as most exchanges do.
Related: Self-custody, Exchange · Read more →
D
DAO
Decentralized autonomous organization: a group that makes decisions by token-holder votes enforced by smart contracts.
Related: Governance token, Smart contract · Read more →
dApp
A decentralized application: an app whose core logic runs as smart contracts on a blockchain.
Related: Smart contract, DeFi · Read more →
DCA (dollar-cost averaging)
Buying a fixed dollar amount on a regular schedule regardless of price.
Related: Cost basis · Read more →
DeFi
Decentralized finance: lending, borrowing and trading through smart contracts rather than banks or companies.
Related: DEX, Smart contract, Stablecoin · Read more →
Depeg
When a stablecoin's price moves away from its target, such as $1.
Related: Stablecoin · Read more →
DEX
Decentralized exchange: smart contracts that let you swap tokens directly from your wallet.
Related: Exchange, DeFi · Read more →
Difficulty
How hard it is to find a valid block in proof of work. Bitcoin adjusts it every 2,016 blocks to keep blocks about 10 minutes apart.
Related: Mining, Proof of work · Read more →
Double spend
Spending the same digital money twice. Blockchains exist largely to prevent it without a central referee.
Related: Consensus mechanism, 51% attack · Read more →
E
ERC-20
The standard format for ordinary tokens on Ethereum, such as USDC.
Related: Token, ERC-721 · Read more →
ERC-721
The standard format for NFTs on Ethereum: each token is unique.
Related: NFT, ERC-20 · Read more →
ETF (spot crypto ETF)
A fund traded on a stock exchange that holds crypto such as bitcoin, letting you invest through a normal brokerage without holding the coins yourself.
Related: Exchange · Read more →
Ether (ETH)
The native coin of the Ethereum network, used to pay gas fees and for staking.
Related: Ethereum, Gwei, Wei · Read more →
Ethereum
A blockchain that runs smart contracts, home to most tokens, DeFi and NFTs. Secured by proof of stake since 2022.
Related: Ether (ETH), Smart contract, Gas · Read more →
Exchange
A platform for buying, selling and swapping crypto. Centralized exchanges are companies; decentralized ones are smart contracts.
Related: DEX, Custodial · Read more →
F
Finality
The point at which a transaction can't realistically be reversed. Showing up fast isn't the same as being final.
Related: Confirmation, Block · Read more →
FOMO
Fear of missing out: the urge to buy because prices are rising and others seem to be getting rich. Scammers exploit it.
Related: Scam
Fork
A change to a blockchain's rules. A hard fork can split one network into two separate coins.
Related: Node · Read more →
G
Gas
The unit measuring the computing work an Ethereum transaction needs. A plain ETH transfer uses 21,000 gas.
Related: Gwei, Base fee · Read more →
Genesis block
The first block of a blockchain. Bitcoin's was mined on January 3, 2009.
Related: Block, Satoshi Nakamoto · Read more →
Gwei
One billionth of an ETH (0.000000001 ETH). Gas prices are quoted in gwei.
Related: Gas, Wei, Ether (ETH) · Read more →
H
Halving
The roughly four-yearly event that cuts Bitcoin's block reward in half. The last was in April 2024 (to 3.125 BTC); the next is expected around April 2028, at block 1,050,000.
Related: Block reward, Bitcoin (BTC) · Read more →
Hardware wallet
A small device that keeps private keys offline and signs transactions inside the device.
Related: Cold wallet, Seed phrase · Read more →
Hash
A fixed-length fingerprint of data. Change the data slightly and the hash changes completely.
Related: Block, Proof of work · Read more →
Hash rate
The total guessing power of a proof-of-work network, a measure of how much work protects it.
Related: Mining, Difficulty · Read more →
HODL
Crypto slang for holding long-term rather than selling, from a misspelled 2013 forum post.
Hot wallet
A wallet app connected to the internet, on a phone, computer or browser.
Related: Cold wallet, Wallet · Read more →
L
Layer 2
A network built on top of a layer 1 that processes transactions more cheaply and posts the results back to it, such as Arbitrum or Base.
Related: Rollup, Bridge, Layer 1 · Read more →
Leverage
Borrowing to make a bigger bet. It multiplies gains and losses, and can wipe out your money quickly in crypto's price swings.
Related: Liquidation
Liquidation
When a lender or exchange automatically sells your collateral because a leveraged position or loan has lost too much value.
Related: Leverage
M
Market cap
Price × number of coins in circulation. A rough measure of a cryptocurrency's total value.
Related: Supply
Meme coin
A token based on a joke or internet meme, usually with no use beyond speculation. Extremely volatile; most become worthless.
Related: Token, Rug pull · Read more →
Mempool
The waiting room of unconfirmed transactions before they go into a block.
Related: Confirmation, Network fee · Read more →
Merkle tree
A way of hashing many transactions in pairs, then pairs of pairs, into one "Merkle root" stored in the block header. It lets you prove one transaction is in a block without downloading the whole block.
Related: Hash, Block · Read more →
MEV
Maximal extractable value: profit made by choosing the order of transactions in a block, for example by "sandwiching" someone's trade.
Related: Slippage, DEX · Read more →
Mining
Using computers to add blocks to a proof-of-work blockchain and earn new coins and fees.
Related: Proof of work, ASIC, Block reward · Read more →
N
Network fee
The fee paid to miners or validators to process a transaction. Called gas on Ethereum.
Related: Gas, Mempool · Read more →
NFT
Non-fungible token: a unique token recording ownership of a specific item, often digital art or a collectible.
Related: ERC-721, Token · Read more →
Node
A computer running a blockchain's software, keeping a copy of the ledger and checking the rules.
Related: Blockchain, Validator · Read more →
Nonce
In mining, the number miners keep changing to search for a valid block hash.
Related: Proof of work, Hash · Read more →
O
Oracle
A service that brings outside data, such as prices, onto a blockchain so smart contracts can use it. If the oracle is wrong or manipulated, the contracts act on bad data.
Related: Smart contract, DeFi · Read more →
P
Phishing
Fake messages, sites or apps that trick you into revealing logins, codes or your seed phrase.
Related: Seed phrase, Scam · Read more →
Pig butchering
A long-con investment scam: a stranger builds a friendship or romance online, then guides you onto a fake crypto platform.
Related: Scam · Read more →
Private key
The secret number that controls your crypto and signs transactions. Never share it.
Related: Public key, Seed phrase · Read more →
Proof of stake
A consensus method where validators lock up coins as a deposit and are chosen to add blocks. Used by Ethereum.
Related: Staking, Validator, Slashing · Read more →
Proof of work
A consensus method where miners compete with computing power to add blocks. Used by Bitcoin.
Related: Mining, Hash, Difficulty · Read more →
Pseudonymous
Using an identifier, like a crypto address, instead of your real name. Most blockchains are pseudonymous, not anonymous.
Related: Address, Block explorer · Read more →
Public key
A key calculated from your private key, used to check your signatures. Your address is made from it.
Related: Private key, Address · Read more →
R
Ripple
A private US company that builds payment software and supports the XRP Ledger. People often say "Ripple" when they mean XRP, the ledger's coin, but buying XRP doesn't make you an owner of Ripple.
Rollup
A kind of layer 2 that bundles many transactions into one batch posted to the main chain.
Related: Layer 2 · Read more →
Rug pull
When a project's creators take investors' money and abandon it, often by dumping their tokens.
Related: Meme coin, Scam · Read more →
S
Satoshi
The smallest unit of bitcoin: 0.00000001 BTC. 100 million satoshis make one bitcoin.
Related: Bitcoin (BTC) · Read more →
Satoshi Nakamoto
The pseudonymous creator of Bitcoin, whose real identity is unknown.
Related: Bitcoin (BTC), Genesis block · Read more →
Scam
A trick to get you to send money or reveal secrets. Crypto scams cost Americans $11.4 billion in reported losses in 2025.
Related: Phishing, Pig butchering, Rug pull · Read more →
Seed phrase
12 or 24 words that can restore every key in a wallet. Also called a recovery phrase. Whoever has it controls your crypto.
Related: Private key, Hardware wallet · Read more →
Self-custody
Holding your own private keys, so no company stands between you and your crypto.
Related: Custodial, Wallet · Read more →
Sidechain
A separate blockchain with its own validators, linked to a main chain by a bridge. Unlike a rollup, it doesn't inherit the main chain's security.
Related: Layer 2, Bridge · Read more →
Slashing
A proof-of-stake penalty that destroys part of a validator's stake for breaking the rules.
Related: Proof of stake, Validator · Read more →
Slippage
The difference between the price you expected and the price you actually got, usually bigger for large orders and thinly traded coins.
Related: Liquidity, Spread · Read more →
Smart contract
A program stored on a blockchain that runs exactly as written when used.
Related: Ethereum, DeFi, Approval · Read more →
Spread
The gap between the price you buy at and the market price (or between buy and sell prices). A hidden cost.
Related: Liquidity · Read more →
Stablecoin
A cryptocurrency designed to keep a steady value, usually $1, such as USDC or USDT.
Related: Depeg, Fiat · Read more →
Staking
Locking up coins to help secure a proof-of-stake network in return for rewards.
Related: Proof of stake, Validator · Read more →
Supply
How many coins exist (circulating supply) or ever will (maximum supply). Bitcoin's maximum is 21 million.
Related: Market cap, Halving · Read more →
T
Token
A crypto asset built on another blockchain using a smart contract, rather than having its own blockchain.
Related: Coin vs. token, ERC-20 · Read more →
Transaction ID (TXID)
The unique code for a transaction, used to look it up on a block explorer.
Related: Block explorer · Read more →
Two-factor authentication (2FA)
A second login step. Use an authenticator app or security key rather than text messages for crypto accounts.
Related: Phishing · Read more →
U
USDC
A US dollar stablecoin issued by Circle, backed by cash and short-term US Treasuries.
Related: Stablecoin · Read more →
USDT (Tether)
The largest US dollar stablecoin by value, issued by Tether.
Related: Stablecoin, USDC · Read more →
UTXO
Unspent transaction output: a chunk of bitcoin locked to a key. Bitcoin tracks coins as UTXOs, like banknotes, rather than as account balances.
Related: Bitcoin (BTC), Transaction ID (TXID) · Read more →
V
Validator
A participant in a proof-of-stake network that stakes coins and proposes and checks blocks.
Related: Proof of stake, Staking · Read more →
Volatility
How much and how fast a price moves. Crypto is far more volatile than most stocks.
Related: Bear market, Bull market
W
Wallet
An app or device that stores your private keys and lets you send and receive crypto.
Related: Hot wallet, Cold wallet, Seed phrase · Read more →
Wallet drainer
Malicious code, usually on a fake website, that tricks you into signing approvals that empty your wallet.
Related: Approval, Phishing · Read more →
Web3
The idea of an internet where people hold their own money, identity and digital items in crypto wallets instead of accounts run by big companies.
Related: DAO, Smart contract · Read more →
Whale
Someone who holds a very large amount of a cryptocurrency, enough to move its price.
Whitepaper
A document describing how a crypto project is supposed to work. Bitcoin's was published in 2008.
Related: Satoshi Nakamoto · Read more →
Wrapped bitcoin (WBTC)
A token on another blockchain, such as Ethereum, that represents bitcoin held by a custodian. It isn't BTC on the Bitcoin network, and you rely on the custodian to redeem it.
Related: Bitcoin (BTC), Bridge · Read more →
Y
Yield
A return paid on crypto for staking, lending or providing liquidity. Always ask where it comes from: high yields usually mean high risk.
Related: Staking, DeFi · Read more →
Yield farming
Moving crypto between DeFi apps to earn fees, interest and reward tokens. Returns can look high but carry hack, impermanent-loss and token-price risk.
Related: Yield, DeFi · Read more →
Z
Zero-knowledge proof
A way to prove a statement is true without revealing anything else. Used for private payments and to prove that rollup batches are valid.
Related: Rollup · Read more →