What Is a Crypto Exchange?

A crypto exchange is a marketplace: buyers on one side, sellers on the other, software in the middle pairing them off. Same idea as a stock exchange, except the thing changing hands is bitcoin or ethereum, not shares in a company.

People call almost anything in crypto an 'exchange', which trips beginners up constantly. A crypto wallet is not an exchange, and an on-ramp like Banxa is not an exchange either. Get those straight and you save yourself money, plus the odd nasty surprise. This is an explainer, not financial advice.

What an exchange actually does

Most exchanges, the big centralised ones at least, run on an order book: a live list of every buy order and every sell order, stacked by price.

You want to buy, someone else wants to sell, and when your price and their price meet, the trade fills and the coins move across. Nobody hands the price down from above, it falls out of what buyers will pay and what sellers will take, second by second. Supply and demand, written down in real time and updated every second the market is open.

Two ways to place an order, worth knowing on day one. A market order takes the best price going right now and fills instantly. A limit order sets your price and waits until the market reaches it, which might be in a minute or never. Speed against control, so beginners usually start with market orders and pick up limits later.

This also explains why one coin shows two slightly different prices on two exchanges at the same moment: different order books, different crowds. Binance launched in 2017 and was the largest exchange by trading volume inside a year, with a book that moves fast enough that the figure on your screen is a snapshot, not a promise.

Centralised exchanges (CEX)

Most people mean a centralised exchange when they say the word: Coinbase, Binance, Kraken. A company runs the platform, keeps the order book, and holds your coins for you.

You sign up, prove who you are, and deposit money by card or bank transfer. Proving who you are is KYC, Know Your Customer, the identity checks regulated platforms run to stay on the right side of the law. Passport, a selfie, sometimes proof of address: annoying, and not optional anywhere reputable.

Once you buy, the platform shows a balance next to your name. That balance sits in a custodial wallet, custodial meaning the company holds the keys, not you. Coinbase listed on Nasdaq on 14 April 2021, the first big crypto exchange to go public, and it custodies coins for tens of millions of people. Convenient, fast, beginner-friendly, and also a single point of failure, which the rest of this guide keeps circling back to.

Decentralised exchanges (DEX)

A decentralised exchange throws the company out: no sign-up, no deposit, no balance held on your behalf, code does the matching.

Uniswap, launched in November 2018, is the one most beginners have heard of. Instead of a company-run order book, it uses smart contracts, small programs on the ethereum network that hold the rules and run the swap automatically, with no employee in the loop and no account anyone can freeze. You connect your own wallet, approve the trade, and the coins land straight with you. That is a non-custodial wallet doing its job: you hold the keys the whole way through, which is self-custody.

No middleman holding your funds is the appeal, but the friction is real. The interface assumes you already know what you are doing, one wrong setting can cost you, every swap carries a network fee, and there is no help desk to ring when it goes sideways. All on you. Most DEXs skip KYC too, which regulators have started circling. Beginners almost never start here, and that is the right call.

Exchange, broker, on-ramp, wallet: four different jobs

Four words, endlessly muddled, doing genuinely different things.

An exchange matches buyers and sellers and lets you trade against the market. A broker sells you crypto at a price it quotes, then sorts out the buying behind the scenes. An on-ramp converts your money into crypto and sends it on, and an off-ramp runs the reverse, turning crypto back into cash in your bank account. A wallet just holds coins, it does not trade, quote prices, or match anyone.

Banxa is an on-ramp and an off-ramp, not an exchange. It has run this plumbing since 2014, across more than 100 payment methods in 100-plus countries, and it sells you crypto and delivers it to a wallet you control. There is no order book, no trading floor, no balance parked on a Banxa account waiting for you to log back in. Money in, crypto out, finished.

Who holds the keys, and why it bites

Leave coins on a centralised exchange and you do not hold the keys to them, the exchange does. What you hold is a promise that the company will hand them back when you ask. A promise, not possession.

Most days that promise is good, some days it is not: Mt. Gox handled the majority of the world's Bitcoin trading until February 2014, when it collapsed and around 850,000 BTC went missing, and creditors are still chasing scraps of it more than a decade on. Then FTX, one of the largest exchanges on the planet and valued in the tens of billions, failed in November 2022 with a customer shortfall of roughly 8 billion dollars. Both times, people who believed they owned crypto found out they owned a court claim instead.

That is the weight behind the oldest line in crypto: not your keys, not your coins. If a company holds the keys, you are trusting the company, not the network. After FTX, plenty of exchanges started publishing 'proof of reserves' to show they hold what they owe. Useful, but it shows assets and not always the debts behind them, so read it as a comfort, not a verdict. Move anything you are not actively trading into a wallet you control. Exchanges are also a hunting ground for crypto scams, so guard your login and trust nobody who messages first.

Fees, spread and why liquidity matters

Exchanges do not run for charity: there are two costs, and the second one hides.

The first is the trading fee, a percentage of each order, often a fraction of a percent on the big platforms, and visible enough. The second is the spread, the gap between the best buy price and the best sell price. You buy a touch high and sell a touch low, and that gap is a real cost whether or not anyone labels it. On small buys, watch for flat minimum fees too, which can swallow a tenth of a twenty-pound order before you have noticed.

Both come back to liquidity: how much of a coin is being bought and sold. Deep liquidity means tight spreads and orders that fill near the price you saw. Thin liquidity means a wide spread, and a single big order can shove the price against you before it fills. The traders and firms supplying the orders everyone else trades against are liquidity providers, and the deepest pools gather around the biggest coins. Bitcoin, the largest by market cap, the total value of every coin in circulation, first crossed 1 trillion dollars in February 2021 and trades so deep that a sizeable order can fill without shoving the price around. A coin with a tiny market cap is the opposite, and can turn into a nightmare to sell at a fair price, however good the chart looked on the way in.

So which one do you actually need?

Most beginners do not need an exchange at all, not at first: you want to own a little bitcoin or ethereum, not day-trade it. For that, an on-ramp sends coins straight to a wallet you control, and you skip the whole question of whether the platform sitting on your money is the next Mt. Gox, because no platform is sitting on it.

Open an exchange account when you genuinely want to trade in and out. But even then, do not leave coins parked on it: buy, then move them off. The people wiped out in 2014 and 2022 had one habit in common: they left it on someone else's platform and assumed tomorrow would look like today.