Crypto Glossary

61 terms in plain English, grouped by where you meet them: core concepts, wallets and keys, transactions and fees, market data, and security. Definitions stay short on purpose — where a term needs more than a paragraph, it links to the guide that explains it properly.

Last reviewed 2026-09-14. Educational information only; nothing here is financial, legal or tax advice.

Core concepts

The vocabulary everything else is built on.

Blockchain: A shared ledger of transactions grouped into blocks, each cryptographically linked to the previous one, maintained by many independent computers rather than a single company. Read the full guide.
Cryptocurrency: A digital asset recorded on a blockchain, where ownership is proven by a private key rather than by an account at an institution. Read the full guide.
Coin: The native asset of its own blockchain, used to pay that network's fees — for example the asset a network charges gas in. Read the full guide.
Token: An asset issued by a smart contract on an existing blockchain. Tokens rely on the host network for security and fees. Read the full guide.
Node: A computer running the network's software, validating and relaying transactions and keeping a copy of the ledger.
Consensus mechanism: The rule that decides who adds the next block and why others accept it. Proof of work uses expended energy; proof of stake uses capital at risk. Read the full guide.
Smart contract: Code deployed to a blockchain that executes exactly as written when called. It can hold and move assets, which is why approvals to contracts matter.
Layer 1: A base blockchain that settles its own transactions and provides its own security. Read the full guide.
Layer 2: A network that processes transactions separately and posts data or proofs back to a Layer 1 for settlement, usually to reduce fees. Read the full guide.
Bridge: A system that represents an asset from one network on another. Bridges add a layer of trust and code risk that holding the native asset does not have. Read the full guide.

Wallets and keys

A wallet stores keys, not coins. These terms describe that relationship.

Private key: The secret that authorises spending from an address. Anyone holding it controls the funds, permanently. Read the full guide.
Public address: The destination string you share to receive funds. Derived from a key pair; safe to publish. Read the full guide.
Recovery phrase (seed phrase): An ordered list of words from which every key in a wallet is derived. It cannot be reset or changed, and it must never be typed into a website. Read the full guide.
Passphrase: An optional extra word added to a recovery phrase, producing a separate wallet. Losing it loses that wallet even if the phrase survives.
Custodial wallet: An account where a company holds the keys. Recovery and support exist; the assets depend on that company. Read the full guide.
Non-custodial wallet: A wallet where you hold the keys. No company can freeze it, and no company can restore it for you. Read the full guide.
Hot wallet: A wallet whose keys sit on an internet-connected device. Convenient, more exposed. Read the full guide.
Cold storage: Keys kept offline, typically on dedicated hardware, so malware on a computer cannot reach them. Read the full guide.
Hardware wallet: A dedicated device that generates and stores keys and signs transactions on its own screen. Read the full guide.
Watch-only wallet: A wallet loaded with a public address only. It can monitor balances but cannot spend. Read the full guide.
Multi-signature: A setup requiring several keys to approve a transfer, removing any single point of failure. Read the full guide.
Token approval: Permission granted to a contract to move a token from your wallet. Unlimited approvals are the mechanism behind many drainer losses. Read the full guide.

Transactions and fees

What actually happens between pressing send and the funds arriving.

Transaction hash (TXID): A unique fingerprint of a transaction, used to look it up on a block explorer. Safe to share. Read the full guide.
Block explorer: A public search interface for a blockchain. It is read-only and never needs a wallet connection or a recovery phrase. Read the full guide.
Confirmation: A block built on top of the block containing your transaction. More confirmations mean a lower chance of reversal. Read the full guide.
Mempool: The waiting area of broadcast but unconfirmed transactions that each node keeps before inclusion in a block. Read the full guide.
Network fee: Payment for limited block space, priced by demand at that moment rather than set by any company. Read the full guide.
Gas: The unit measuring computational work on Ethereum-style networks. The fee is gas used multiplied by the price per unit. Read the full guide.
Nonce: A counter ordering transactions from one account. A pending low-nonce transaction blocks everything behind it. Read the full guide.
Replace-by-fee (RBF): Replacing an unconfirmed transaction with a higher-fee version, where the network and wallet support it. Read the full guide.
Memo / destination tag: An identifier some networks attach to a transfer so a shared deposit address can tell customers apart. Read the full guide.
Finality: The point at which a transaction is considered irreversible. Probabilistic on proof-of-work networks; explicit in many proof-of-stake designs. Read the full guide.
Satoshi: The smallest Bitcoin unit: one hundred-millionth of a bitcoin. Read the full guide.

Markets and trading terms

The numbers on a market page, and what they do not mean.

Market capitalisation: Price multiplied by circulating supply. A size comparison, not a measure of money invested. Read the full guide.
Circulating supply: Units considered available in the market today, as estimated by the data provider. Read the full guide.
Fully diluted valuation (FDV): Today's price applied to total or maximum supply — a hypothetical, not a forecast. Read the full guide.
24-hour volume: Value traded over the period. Every trade has a buyer and a seller, so volume is not net inflow. Read the full guide.
Liquidity: How much can be traded without moving the price. Thin liquidity makes exits expensive. Read the full guide.
Slippage: The gap between the expected price and the executed price, which grows with order size on thin markets. Read the full guide.
Centralised exchange (CEX): A company-operated trading venue that holds customer funds and matches orders internally. Read the full guide.
Decentralised exchange (DEX): Trading through smart contracts directly from a self-custodial wallet, with no company holding the funds.
Stablecoin: A token designed to track the value of a reference asset, most often the US dollar. Tracking is a design goal, not a guarantee. Read the full guide.
Depeg: When a stablecoin trades away from the value it aims to track. Read the full guide.

Security terms

The attack vocabulary worth recognising before you meet it.

Phishing: A fake site, message or app designed to capture a recovery phrase, credentials or a malicious signature. Read the full guide.
Wallet drainer: A kit that converts a single approval or signature into an authorised transfer of your assets. Read the full guide.
Address poisoning: Sending tiny transfers from a look-alike address so that it appears in your history and is copied by mistake later. Read the full guide.
Clipboard malware: Software that silently swaps a copied crypto address for the attacker's address. Read the full guide.
SIM swap: An attacker taking over a phone number to intercept SMS codes and reset account access. Read the full guide.
Advance-fee scam: Any scheme requiring a payment before a promised release of funds — including recovery, tax and unlock fees. Read the full guide.
Blind signing: Approving a request whose contents you cannot read. The core technique behind drainer losses. Read the full guide.
Dust transfer: A tiny unsolicited transfer, often used to seed a look-alike address or a scam token into your history. Read the full guide.

DeFi and cross-chain

Vocabulary you meet in decentralised finance and when moving assets between chains. Each of these is explained in full, with its risks, in the DeFi reference and the bridge guide.

DeFi (decentralised finance): Financial applications that run as smart contracts on a public blockchain instead of being operated by a company, with no support desk, chargeback or deposit insurance behind them. Read the full guide.
Automated market maker (AMM): A decentralised exchange design that prices trades with a formula based on the assets held in a pool, rather than matching buyers with sellers. Read the full guide.
Liquidity pool: The pot of assets supplied by users that an automated market maker trades against; suppliers earn a share of trading fees. Read the full guide.
Price impact: How much your own trade moves the pool's price, which grows with trade size relative to pool depth. Distinct from slippage. Read the full guide.
Impermanent loss: The value gap between holding two assets and depositing them into a liquidity pool, which widens as their relative price diverges and becomes real on withdrawal. Read the full guide.
Collateral and liquidation: Assets locked to borrow against, and the automatic sale of those assets by the protocol when their value falls past its threshold. Read the full guide.
Oracle: The mechanism that feeds external data, usually prices, into a smart contract. Manipulated or stale oracles are a recurring cause of losses. Read the full guide.
Wrapped token: A token representing an asset from another chain, backed by the original being locked or held. It is a claim on that arrangement, not the asset itself. Read the full guide.
Lock and mint: The common bridge design: the original asset is locked on the source chain and a representative token is minted on the destination chain. Read the full guide.
Cost basis: Generally what an asset cost you to acquire — the starting point for working out gain or loss on a later disposal under US property treatment. Read the full guide.