Most of what happens inside an exchange never touches a blockchain. Your deposit arrives on-chain, and after that the firm simply updates rows in its own database as you trade. Matching happens in an internal <a href="/glossary/order-book/">order book</a>, which is why fills are instant and fees can be small. The blockchain only sees your activity again when you withdraw, and that single fact explains almost everything else about how these platforms behave.
Because a company sits in the middle, it has obligations and powers a protocol does not. Expect identity checks under <a href="/glossary/kyc/">KYC</a> rules, document uploads, withdrawal limits and the ability to freeze an account. That is not necessarily sinister — it is what operating a regulated financial business looks like — but it does mean access to your balance depends on a firm's decisions, its solvency and its security, all at once.
The plain warning is worth stating without softening: coins left on an exchange are the exchange's coins as far as the chain is concerned, and customers of failed platforms have historically become unsecured creditors. Keep on the platform only what you are actively trading, and move the rest out. The walkthrough on <a href="/toolkit/how-to-move-crypto-off-an-exchange/">moving crypto off an exchange</a> covers doing that safely, and a <a href="/glossary/decentralized-exchange/">decentralised exchange</a> offers the opposite trade-off: you keep custody, but you also keep every responsibility that comes with it.
How to Buy Your First Crypto Safely
Key takeaways
- Trades inside an exchange are database entries, so only deposits and withdrawals are real blockchain transactions.
- An account balance is a claim on a company, which is a different thing from owning coins outright.
- Enabling strong two-factor authentication and withdrawing to your own wallet removes the two most common ways people lose funds on these platforms.
Centralised Exchange (CEX) — frequently asked questions
Is a centralised exchange safe to use?
Reputable platforms are fine for buying, selling and converting, and most people start there. The risk is not usually the trade itself but the habit of leaving balances behind afterwards. Treat an exchange as a place you pass through: verify your identity properly, turn on app-based two-factor authentication, test small withdrawals first, and keep long-term holdings in a wallet whose keys belong to you.
Why does an exchange charge a fee to withdraw?
A withdrawal is a real on-chain transaction, so the exchange pays a network fee to have it confirmed, and it usually passes that on with a margin. The size varies by network, which is why moving the same value can cost very different amounts depending on the chain you choose. Batching withdrawals rather than making many small ones normally works out cheaper.
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