The term you’re looking for is private key. It’s the secret key that proves control or ownership of a blockchain account, and it must be kept safe because if it’s leaked or lost, access can be compromised or permanently lost.

Quick scoop

In blockchain, a private key is the confidential part of a key pair used to sign transactions and authorize account access. The matching public key or wallet address can be shared, but the private key should never be exposed.

Why it matters

  • Needed to claim ownership: Whoever controls the private key can prove control of the account.
  • Managed by the user: In non-custodial wallets, the user is responsible for storing it securely.
  • Must not be leaked or lost: Sharing it can let others take the funds, and losing it can mean losing access permanently.

If you want, I can also give you a one-line definition you can use for a post or glossary entry.