Attestation
A validator's cryptographically-signed vote that a block is valid — the building block of Proof of Stake consensus.
An attestation is a validator’s signed statement agreeing that a particular block is valid and represents the correct chain head. In Ethereum’s Proof of Stake, validators are assigned to attest each epoch, and it’s the accumulation of these votes — weighted by stake — that drives consensus and finality.
Attesting is a validator’s core duty; doing it correctly and on time earns rewards, while missing attestations incurs small penalties and contradictory ones risk slashing. Collectively, honest attestations from validators controlling two-thirds of the stake finalize the chain. The mechanism replaces Proof of Work’s energy expenditure with a voting process secured by economic stake — the essence of how PoS reaches agreement.