Bitcoin wallets explained: custody, keys and backups

A Bitcoin wallet does not hold coins. It holds the keys that let you move coins recorded on the public blockchain. The distinction matters: the ledger is shared and public, while control sits with whoever can produce the right cryptographic signature. Lose the keys and the coins remain on the chain, unreachable to you.

Keys, addresses and what a wallet actually stores

A wallet generates a private key and derives a public key and addresses from it. The private key signs transactions; the address receives funds. Modern wallets usually derive many keys from a single seed, which is why one recovery phrase can restore a whole set of addresses. Treat the wallet as a key manager and a signing tool, not as a vault of assets.

Custodial versus self-custody

With a custodial setup, a service holds the keys and you hold an account. That is convenient and familiar, but you depend on that service to stay solvent, honest and operational, and you accept its terms. With self-custody, you hold the keys and therefore the responsibility. No support desk can reverse a mistaken transfer or reset your access. The trade-off is control against convenience, and it should be a deliberate choice rather than a default.

Hot versus cold storage

A hot wallet runs on a device connected to the internet, which suits small balances and frequent movement. A cold wallet keeps keys offline, signing only when needed, which reduces exposure to malware and remote attacks. Cold storage does not remove risk: loss, damage and user error remain. Many people split holdings by purpose, keeping spending money hot and savings cold.

The recovery phrase

• It is the master backup: anyone who reads it can spend the funds.
• Never share it, and never type it into a website, chat or support form.
• Never photograph it or store it in cloud notes, email or messaging apps.
• Write it on durable material and keep it somewhere private and physically secure.
• Be wary of anyone who asks for it; legitimate services do not need it.

Backups and a first test

A backup is only useful if it works. Verify a recovery phrase by restoring it on a spare device before relying on it, and keep the backup separate from the device it protects. For any new address, send a small test transfer first and confirm it arrives and can be spent before moving a larger amount. Check the address on the device screen, not only on a computer. Slow, deliberate steps at the start prevent the errors that cannot be undone later.