When you buy coins on an app, you see a balance with your name on it. It feels like a bank account. But does not work like a bank, and the difference becomes very real on the day something goes wrong. This lesson explains where your coins actually are, who controls them, and the one secret you must never give to anyone.
Before we start: what do you think?
You buy coins on an exchange, and they show up in your account there. Who controls those coins?
✗ The account is in your name, but the coins sit in addresses whose keys the exchange holds.
✓ Right: you have a promise from the exchange, and it can move, freeze or lose the coins.
✗ A blockchain only records payments; whoever holds the key decides where coins go.
✗ Your bank only sent the money; it has no control over the coins after that.
Coins live on the blockchain, keys move them
Your coins are not stored inside an app or a device. They are entries in the 's shared record book, linked to an address, which is a long string of letters and numbers.
To move coins from an address, you need its private key. A is a secret number. Whoever has it can send the coins anywhere, and the network will accept the payment. There is no name check, no phone call and no second chance.
So the real question is never "where are my coins?" It is "who holds the key?"
Quick check
What do you need to move coins from an address?
Exchanges: convenient, but you hold a promise
A crypto exchange is a company where people buy and sell coins, usually for euros, dollars or other coins. It is the most common starting point.
When you keep coins on an exchange, the exchange holds the keys for you. This is called custody. Your balance is the exchange's promise to give you those coins when you ask. That is convenient: you can log in with a password, reset it if you forget it, and trade in seconds.
But a promise is only as good as the company behind it. Exchanges can:
- freeze withdrawals, for a day or for good;
- be hacked;
- go bankrupt, sometimes after using customers' coins for their own bets.
This is not theory. Exchanges have collapsed before, including some very large ones. Customers could not withdraw, and many waited years to get back part of their money, or got nothing. Crypto usually has no deposit protection like a bank account. EU regulators warn that buyers of crypto have little recourse or protection, and can lose all the money they put in.
In the EU, crypto service providers need an authorisation under a law called MiCA, and the EU markets regulator publishes a register of the authorised ones. Being on the register does not mean a company cannot fail. If you live outside the EU, check what your own country's regulator says.
Quick check
What does your balance on an exchange really represent?
Your own wallet: full control, full responsibility
A crypto wallet is an app or a small device that holds your private keys. It does not hold coins. It holds the keys that move them. When you use your own , nobody can freeze your coins, but nobody can rescue you either.
There are two broad kinds:
- A hot wallet is an app on a phone or computer that is connected to the internet. It is easy to use, but malware or a fake app can steal from it.
- A cold wallet keeps the keys offline, often on a small device made for this job. It is safer from online attacks, but you can still lose it or be tricked into approving a bad payment.
When you set up a wallet, it shows you a seed phrase: usually 12 or 24 ordinary words in a set order. The can rebuild all your keys on any device. That makes it the most important thing you own in crypto.
Rules for your seed phrase:
- Never share it. Not with friends, not with "", not with anyone. No real company will ever ask for it.
- Never type it into a website. Not to "verify", "sync", "unlock" or "claim" anything. A page that asks for it is a theft attempt.
- Write it on paper. Do not take a photo of it, and do not save it in email, notes or cloud storage.
- Keep the paper somewhere safe, and think about fire and water.
If someone gets your seed phrase, they can empty your wallet in a minute. If you lose it and your device breaks, your coins are gone for good. There is no "forgot password" button.
Quick check
Name two things you must never do with your seed phrase.
Mistakes that cannot be undone
Blockchain payments are final. Two common mistakes:
- Wrong address. One wrong character, or a pasted address that malware swapped, and the coins go to someone else.
- Wrong network. Some coins exist on more than one blockchain. If you send on a network the receiver does not support, the coins can be lost.
That is why careful people always send a small test payment first.
Worked example: Moving $1,000 from an exchange to your own wallet
You have $1,000 of coins on an exchange. Imagine the withdrawal fee is $2 for each withdrawal. (Fees differ by coin, network and exchange. These numbers are only an example.)
With a test first:
- Send $20. After the fee, $18 arrives. You check that it arrived at the right address, on the right network.
- Send the remaining $980. After the fee, $978 arrives.
- In total, $996 arrives and you paid $4 in fees.
Without a test:
- Send all $1,000 at once. If everything is correct, $998 arrives and you paid $2.
- If the address or network was wrong, all $1,000 is gone.
The test costs you $2 extra. It is the cheapest insurance in crypto.
Key takeaways
- Coins live on the blockchain. The private key decides who can move them.
- On an exchange, the exchange holds the keys. You hold a promise, and exchanges have failed before.
- In your own wallet, you hold the keys. Nobody can freeze your coins, and nobody can rescue you.
- Your seed phrase rebuilds all your keys. Never share it, and never type it into a website.
- Payments are final, so send a small test first.
Try this
If you already own crypto, write down where each part of it is kept: which exchange or which wallet, and who holds the keys. If you use a wallet, check without opening anything online that your seed phrase is written on paper and stored safely, and nowhere else. If you do not own crypto, read the glossary entries for private key and seed phrase, and explain them to someone in your own words.