An account discriminator is an 8-byte hash prefix added to the beginning of every account created by an Anchor smart contract. The discriminator identifies which type of account it is — for example, a lock account versus a staking position account.

Discriminators are derived by hashing the account type name. When an Anchor program reads an account, it verifies the discriminator matches the expected type before processing it. This prevents type confusion attacks where malicious accounts could be passed as legitimate ones.

Account discriminators are an Anchor-specific security feature. They are automatically added and verified by the framework, providing an additional layer of type safety on top of Solana's core account model.