What is a private key?
A private key is a 256-bit number (usually represented as 64 hexadecimal characters) that is mathematically linked to your wallet's public address. It is used to sign transactions, proving that you authorise them. Anyone with your private key has complete, irrevocable control over your wallet.
Private key vs seed phrase
Your seed phrase (12 or 24 words) is a human-readable representation of your private key. They are equivalent — anyone with either can control your wallet. Most users interact with seed phrases rather than raw private keys.
How to protect your private key
- Never share it — no legitimate service will ever ask for your private key
- Store offline — write your seed phrase on paper, store in a safe place
- Never type it online — phishing sites harvest private keys
- Use hardware wallets for large holdings — private key never leaves the device
- Multiple backups — store copies in separate physical locations
What happens if you lose your private key
There is no recovery. Unlike a bank password, there is no "forgot my key" option. If you lose your private key and have no backup, your funds are permanently inaccessible. This is the most important concept in crypto self-custody.
Hardware wallets
Hardware wallets (Ledger, Trezor) store your private key on a dedicated device that never connects to the internet. Even if your computer is hacked, your private key remains secure.