It depends on who holds the private key: you, in a wallet of your own, or the platform where you have an account.
A platform account vs. your own wallet
When you buy crypto on an exchange and leave it there, the platform is the one keeping the record, the same way a bank keeps the record of the money in your account. This is the “custodial” model: the platform effectively holds the assets on your behalf, and you only have a claim to ask for them back. Your own wallet works differently: the assets are recorded directly on the blockchain, in your name, and access to them is controlled by a key that you hold, not the platform.
A wallet of your own can be a phone app, a browser extension, or a dedicated physical device (a “hardware wallet,” kept offline for extra safety). In every case, the principle is the same: the app or device doesn’t “contain” your assets (they exist on the blockchain); it only stores the key that controls them.
What the private key is
A private key is a mathematically generated string of characters that proves the right to move the funds tied to it. Whoever has it can transfer the assets; whoever doesn’t, can’t - no matter how much they “know” the assets are theirs. In practice, a wallet of your own doesn’t show you the private key directly: it gives you a recovery phrase of 12 or 24 words, from which the key can be rebuilt at any time, on any compatible device.
“Not your keys, not your coins”
This phrase has been circulating in the crypto community for a long time, and it sums up the difference above exactly: if you don’t hold the private key, you don’t really hold the assets: you’re relying on the good faith and security of the platform holding them for you. If the platform gets hacked, goes bankrupt, or locks your account by mistake, recovery depends on its policies, a regulator, or a court, not on you directly. With a wallet of your own, the risk shifts: you no longer depend on a third party, but if you lose the recovery phrase, no one (not the platform, not Coin Bank) can rebuild it for you.
When each one makes sense
A platform account makes sense if you trade often, if you’d rather have someone else handle the technical side, or if the amount doesn’t justify the extra care a wallet of your own requires. A wallet of your own makes sense if you’re holding crypto for longer, if you want full control and independence from any one platform, or if the amount is large enough that the risk of a third-party platform matters more than the convenience. Many people use both: a platform for everyday transactions and a wallet of their own for what they want to keep.
What to remember
- On a platform, the platform holds the assets (custodial); in a wallet of your own, the key and the control are yours.
- Whoever holds the private key controls the funds. A lost or shared recovery phrase means lost or shared access, irreversibly.
- There’s no universally correct choice: it depends on how often you trade, how much control you want, and how much it matters to you not to depend on a third party.