How Exchanges Work

What Is a Crypto Exchange?

A cryptocurrency exchange is a platform where you can buy, sell, and trade digital assets. There are two main types: Centralized Exchanges (CEXs) like Coinbase, Kraken, and Binance operate similarly to traditional stock brokerages — a company holds your assets and matches buy/sell orders. Decentralized Exchanges (DEXs) like Uniswap and Jupiter run entirely on smart contracts with no central company involved — you trade directly from your own wallet.

CEX vs DEX: The Basic Difference

CEXs are easier for beginners: you create an account, deposit money, and buy crypto with a familiar interface. The exchange holds your crypto (custodial). DEXs give you full control of your assets at all times (non-custodial), but require a wallet and more technical knowledge. The famous phrase 'not your keys, not your crypto' refers to the risk of leaving assets on a CEX.

• CEX: Easy to use, fiat on-ramp, customer support, but you don't control your keys
• DEX: Full control of assets, no KYC required, but harder to use and no customer support
• Most beginners start with a CEX, then learn DEXs as they gain experience

How Order Books and AMMs Work

CEXs use order books — a real-time list of buy orders (bids) and sell orders (asks) at different prices. When a bid matches an ask, a trade executes. The difference between the highest bid and lowest ask is the 'spread.' Market orders execute immediately at the best available price. Limit orders execute only when the price reaches your specified level.

Automated Market Makers (AMMs)

DEXs typically use AMMs instead of order books. AMMs use liquidity pools — smart contracts holding pairs of tokens funded by liquidity providers (LPs). The price is determined by a mathematical formula (usually x * y = k, the constant product formula). When you swap Token A for Token B, you add A to the pool and remove B, which changes the ratio and thus the price. This is why large trades cause more 'slippage' — price impact from changing the pool ratio.

Understanding Fees

• Maker fees: Paid when you add liquidity to the order book (limit orders that don't fill immediately) — typically 0.01-0.1%
• Taker fees: Paid when you remove liquidity (market orders, limit orders that fill immediately) — typically 0.05-0.2%
• DEX swap fees: Usually 0.3% per swap on Uniswap V2, variable on V3 (0.01-1%)
• Gas fees: On DEXs, you also pay blockchain transaction fees on top of swap fees
• Spread: The hidden cost of the bid-ask gap on CEXs, or slippage on DEXs

Advanced Exchange Mechanics

Concentrated liquidity, introduced by Uniswap V3, allows LPs to provide liquidity within specific price ranges rather than across the entire price curve. This dramatically increases capital efficiency — an LP providing liquidity in a narrow range earns fees as if they had deployed many times more capital across the full range. However, if the price moves outside their range, they stop earning fees and may suffer greater impermanent loss.

Intent-Based Trading and Solvers

The latest evolution in DEX design is intent-based trading, pioneered by CoW Protocol. Instead of executing a swap on-chain directly, users sign an 'intent' (I want to swap X for Y). Professional 'solvers' then compete to fill that intent at the best possible price, potentially matching peer-to-peer trades, routing through multiple pools, or using private liquidity. This eliminates MEV extraction (sandwich attacks) and often provides better execution than traditional AMMs.

Exchange Risks and Regulation

The FTX collapse in 2022 (losing $8+ billion in customer funds) demonstrated the danger of centralized exchange custody. Since then, regulatory frameworks like MiCA in Europe require proof of reserves and segregated customer funds. Many exchanges now publish regular Merkle tree proof-of-reserves attestations. On the DEX side, smart contract risk remains the primary concern — AMM pools can be exploited through flash loan attacks, oracle manipulation, or governance attacks on upgradeable contracts.