What Is a Crypto Exchange?

What Is a Crypto Exchange?

A crypto exchange is where buyers and sellers meet to trade. It matches orders and sets a live price, much like a stock exchange does for shares. It is usually the first place a newcomer buys crypto and the main venue where prices are discovered, the bustling marketplace at the centre of the crypto economy, where the constant tug of buy and sell orders settles on the price you see quoted everywhere.

Centralised vs Decentralised Exchanges

How an Exchange Works

The two types work quite differently under the hood. A centralised exchange (CEX) runs a traditional "order book", matching buyers and sellers, much like a stock exchange, and takes custody of users’ funds to make trading fast and simple. You deposit money, place market or limit orders, and the exchange settles the trade internally. A decentralised exchange (DEX), by contrast, has no central operator: it runs on smart contracts, and most use "liquidity pools" rather than an order book, communal pots of tokens supplied by users, against which you trade directly from your own wallet at a price set by a formula (an "automated market maker"). The CEX trades custody for convenience and a familiar experience; the DEX trades convenience for self-custody and permissionless access. Both are simply mechanisms for discovering a price and swapping one asset for another, but they embody crypto’s two competing instincts: ease of use versus true decentralisation.

The Custody Risk: Not Your Keys

The convenience of a centralised exchange comes with a serious and often underappreciated risk: when the exchange holds your keys, you do not truly control your coins, you hold an IOU from the exchange. This exposes you to "counterparty risk", the danger that the exchange itself fails, is hacked, freezes withdrawals, or turns out to have mishandled customer funds. Crypto history is scarred with examples, most infamously the sudden collapse of the FTX exchange in late 2022, which trapped billions of dollars of customer money and helped drag CFGI’s crypto reading to a low of 16 as fear swept the market. This is the hard lesson behind the crypto mantra "not your keys, not your coins": funds left on an exchange are, in a meaningful sense, not fully yours. The common-sense response is to treat a centralised exchange as a place to trade rather than a place to store wealth, moving long-term holdings into self-custody, while accepting the exchange’s convenience for active trading. Convenience and security pull in opposite directions, and where you land is a personal choice, but the risk is real and worth respecting.

Why Are Exchange Flows a Sentiment Signal?

Exchanges are the doorway between holding and selling. To sell a coin you usually have to move it onto an exchange first, so a surge of coins flowing in signals that holders are preparing to sell, which reads as fear. The reverse, stablecoins flowing in, signals buyers loading up, which reads as greed. Because these flows happen on the public blockchain, CFGI can read them and fold them into the Crypto Fear and Greed Index as one of its 10 indicators. The exchange is, quite literally, where the crowd shows its hand: the act of moving coins to a venue where they can be sold, or moving stablecoins there to buy, is a statement of intent that, on a transparent blockchain, the whole market can read.