Crypto glossary: every term, in plain English
Crypto comes with its own language, and most of it is explained badly. This dictionary gives you the definition in one short paragraph — what it is, why it matters, and the one thing beginners usually get wrong. 20 terms so far, grouped by topic. No jargon in the definitions.
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Crypto basics 7
Altcoin
An altcoin is any cryptocurrency that isn't Bitcoin. The word blends 'alternative' and 'coin' and covers thousands of projects — from Ethereum, which runs smart contracts, to stablecoins pegged to the dollar. Altcoins usually trade in pairs against Bitcoin, tend to move with it, and are typically more volatile and riskier than Bitcoin itself.
Definition →Bull and Bear Market
A bull market is a prolonged period of rising prices powered by optimism; a bear market is a prolonged decline of typically 20% or more from a peak, powered by fear. Crypto's cycles are more extreme than stocks': bulls have produced 10x-plus gains across whole markets, and bears have erased 70–90% of many coins' value. Each phase demands a different behavior from beginners.
Definition →Coin vs Token
A coin is the native currency of its own blockchain — Bitcoin on the Bitcoin network, ETH on Ethereum. A token is issued on top of an existing blockchain using a smart contract, the way USDT exists on Ethereum. The distinction matters for risk: coins secure their own network, while tokens depend entirely on whatever platform hosts them and on the issuer behind them.
Definition →DeFi
DeFi (decentralized finance) is financial services rebuilt on public blockchains without banks or brokers in the middle. Instead of an institution holding your money, smart contracts do: you can lend coins for interest, swap tokens, or borrow against collateral, 24/7, from a self-custody wallet. The upside is open access; the cost is that you, not a bank, absorb every mistake and every hack.
Definition →Market Cap
Market cap (capitalization) is a cryptocurrency's current price multiplied by the number of coins in circulation. It estimates the total value of all coins together, which is why a $2 coin isn't 'cheaper' than a $2,000 coin — price alone tells you nothing about size. Market cap is the standard way to rank, compare, and size crypto projects.
Definition →Stablecoin
A stablecoin is a cryptocurrency built to keep a constant value — almost always one US dollar. Traders use it to park money without leaving crypto, send dollars worldwide in minutes, and buy other coins. The three designs are fiat-backed (reserved dollars), crypto-backed (over-collateralized loans), and algorithmic. Stablecoins avoid market volatility but carry their own risk: the peg can break.
Definition →Volatility
Volatility measures how sharply and unpredictably a price moves over time. Crypto is extreme even by tech-asset standards: Bitcoin has repeatedly fallen more than 70% from its peaks and regularly moves 5–10% in a day, while smaller coins commonly move more. High volatility means bigger potential gains, bigger potential losses, and a real possibility you'll be tempted to sell at the worst moment.
Definition →Wallets & security 7
Cold Wallet
A cold wallet is any wallet whose private keys have never touched the internet. The keys live on an offline device — typically a hardware wallet — and transactions are signed offline before being broadcast by a connected device. Because there's no online key to steal, malware and phishing can't reach your funds. Cold storage is the standard for meaningful long-term holdings.
Definition →Hardware Wallet
A hardware wallet is a purpose-built device — roughly the size of a USB stick — that stores your private keys offline and signs transactions on its own secure chip. Your computer or phone proposes the transaction, but only the device can authorize it, and it confirms details on its own screen. Brands like Ledger and Trezor dominate the category. It's the standard upgrade once your crypto is worth protecting seriously.
Definition →Hot Wallet
A hot wallet is a crypto wallet whose private keys live on an internet-connected device — a phone app, browser extension, or exchange account. It's the convenient everyday option: sending, swapping, and interacting with apps takes seconds. The cost is exposure — anything online can be attacked, phished, or malware-scraped — so hot wallets should hold spending money, not savings.
Definition →Phishing
Phishing is a scam where attackers impersonate a service you trust — an exchange, wallet, or support team — to trick you into handing over access. In crypto it takes three main forms: fake login pages that capture your credentials, fake support agents who ask for your seed phrase, and malicious websites that request a wallet approval signature that drains your funds. Crypto phishing is irreversible: stolen funds are usually gone within minutes.
Definition →Public Key
A public key is the shareable half of a cryptographic key pair used to receive crypto. It's derived from your private key and works like a bank account number: anyone can use it to send you funds or verify your signatures, but it grants no ability to spend. Your private key, which never leaves your wallet, is what actually authorizes transactions.
Definition →Seed Phrase
A seed phrase (recovery phrase) is a list of 12–24 ordinary words generated when you create a self-custody wallet. It is the master key to every account in that wallet: anyone who reads it can spend your crypto from anywhere, and no password reset exists. Store it offline, on paper or metal, never as a photo, file, or cloud note — and never share it with anyone, ever.
Definition →Two-Factor Authentication (2FA)
Two-factor authentication (2FA) requires a second proof of identity when you log in — usually a rotating 6-digit code — so a stolen password alone can't open your account. For crypto, the app-based code (authenticator app or passkey) is the standard; SMS codes are weaker because phone numbers can be hijacked through SIM-swap attacks. Enable 2FA on every exchange account before depositing anything.
Definition →Trading & exchanges 6
FUD
FUD stands for 'fear, uncertainty, and doubt' — crypto slang for information (or disinformation) that spreads fear about a coin, project, or the market. The word is used both ways: sometimes it names genuine manipulation, like coordinated panic-spreading to buy in cheaper; more often it's a muzzle that holders throw over any criticism. Learning to tell real risk from label-as-dismissal is a core beginner skill.
Definition →Gas Fee
A gas fee is the price you pay to have a transaction processed and recorded on a blockchain — it compensates the validators who run the network. On Ethereum, gas is paid in ETH and its price moves with network congestion, from cents in quiet hours to tens of dollars at peak mania. Other chains price fees differently and usually far cheaper. Skip the fee and your transaction simply never confirms.
Definition →KYC
KYC (Know Your Customer) is the identity-verification process regulated crypto exchanges must run before letting you trade: you submit a government ID and a live selfie, sometimes proof of address, and verification usually completes within minutes to a day. It exists to stop money laundering and fraud, and it cuts both ways — it exposes exchanges to law enforcement but also protects you, since verified platforms are far harder to walk away from with stolen funds.
Definition →Limit Order
A limit order is an instruction to buy or sell at a specific price or better — and never worse. Buy limit at $60,000 fills at $60,000 or lower; sell limit at $70,000 fills at $70,000 or higher. It trades certainty of execution for certainty of price: you might wait, or the market may never reach your price at all. Its opposite is the market order, which executes instantly at whatever the current price is.
Definition →Order Book
An order book is the exchange's live ledger of every open order: on one side the bids (what buyers will pay) and on the other the asks (what sellers demand), each with price and size. The gap between the best bid and best ask is the spread, and the sizes stacked at each level show depth — how much you can trade before moving the price. Reading it tells you a market's real liquidity before you commit money.
Definition →Slippage
Slippage is the difference between the price you expect when you place a trade and the price at which it actually executes. It happens because markets move between click and confirmation, and because large orders eat through multiple price levels. Small slippage is normal on liquid markets; on thin coins or volatile days it can silently cost several percent. You control it with limit orders and sane slippage tolerances.
Definition →Definitions are educational only and are not financial advice. New terms are added regularly — if one you need is missing, ask us in our Telegram community and we'll add it.