Private Key
A private key is a secret, randomly generated number that authorises spending from a crypto address. Whoever holds the private key controls the funds, so protecting it is the single most important part of self-custody.
How it works
The private key is mathematically paired with a public key, from which a wallet address is derived. The link only works in one direction: it is easy to produce the public key and address from the private key, but practically impossible to reverse the process. To spend funds, the wallet uses the private key to create a digital signature that the whole network can verify without ever seeing the key itself.
Why it matters
Because a private key cannot be reset like a password, losing it usually means losing the funds permanently, and exposing it lets anyone drain the wallet. This is why keys are normally backed up as a seed phrase and kept offline.
Example
When you approve a transaction in a wallet app, it is your private key signing that transaction behind the scenes.
Private Key: Frequently Asked Questions
What does a private key actually do?
What happens if I lose or expose my private key?
Why can't someone derive my private key from my address?
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