Private Key
The secret number that proves ownership of crypto and authorizes spending it; whoever holds it controls the funds.
A private key is a very large random number — for Bitcoin, 256 bits, a value so vast that guessing one is hopeless. It mathematically pairs with a public key and an address. Spending requires signing the transaction with this key.
Control of the key is control of the money. There's no account behind it and no password to reset. Leak it and your coins can be moved in seconds. This is why wallets bury the raw key behind a seed phrase you back up and never share.
Related terms
A key derived from your private key that others use to verify your signatures and that forms your address.
Seed PhraseA list of 12 or 24 ordinary words that backs up a wallet and can restore all its keys.
AddressA short string of letters and numbers that identifies where crypto can be sent on a blockchain.
Digital SignatureA cryptographic proof that a specific keyholder authorized a message, and that it hasn't been altered since.