An exchange is a marketplace where people buy, sell, or trade cryptocurrencies like Bitcoin and Ethereum, either for other digital assets or for traditional (fiat) currency. In practice, exchanges help users discover prices, find counterparties, and execute trades in a structured way.
How crypto exchanges work
Most exchanges list assets in trading pairs, such as BTC/USD or ETH/USDC, so a trade is effectively an exchange from one asset to another. On many platforms, orders are placed into an order book, where buy and sell offers are matched. Some exchanges also offer instant “convert” features that quote a rate and execute immediately, which is convenient but can include a wider spread.
Exchanges typically charge fees, often as a percentage of the trade, and may offer extra services like custody wallets, recurring buys, or on platform transfers. For example, a user might deposit fiat via bank transfer, buy BTC, then swap part of it into a stablecoin to reduce volatility exposure, all without leaving the platform.
Centralized vs decentralized exchanges
Centralized exchanges (CEXs) are operated by companies that run the trading infrastructure and, in many cases, hold customer funds in custodial wallets. They often support fiat on ramps and off ramps and may require identity verification, depending on jurisdiction.
Decentralized exchanges (DEXs) run through smart contracts on a blockchain. Instead of a company matching orders, many DEXs use automated market makers, where liquidity pools enable swaps like ETH for USDC directly from a user’s wallet. This can improve user control over funds, but it also introduces smart contract and network fee considerations.
Why this matters in crypto
Exchanges are the primary gateway between traditional finance and crypto markets. Understanding how they work, and the tradeoffs between CEX and DEX models, helps users manage fees, custody risk, and execution quality while participating more safely in the broader crypto ecosystem.