Attestation

What is an Attestation?

An attestation is a cryptographically signed vote from a validator confirming the validity of a proposed block. In Ethereum's Proof of Stake system, attestations are the primary mechanism through which validators reach consensus on the canonical chain.

How Attestations Work

When a block is proposed, validators in the current committee review it and submit attestations if they deem it valid. An attestation contains:

• The block being voted on (target)
• The checkpoint being finalized (source)
• The validator's signature
• Committee assignment information

Attestations in Ethereum

Ethereum validators must submit one attestation per epoch (every 6.4 minutes). Each attestation serves multiple purposes:

Attestation Rewards

Submitting correct, timely attestations earns validators the majority of their rewards. Late or missing attestations reduce earnings. Incorrect attestations (voting for wrong blocks) can result in penalties.

Aggregation

Individual attestations with identical votes are aggregated into single aggregate attestations. This compression reduces on-chain data requirements and improves scalability. Aggregators combine attestations from their assigned validators.

Finality Through Attestations

When enough validators (2/3 of staked ETH) attest to a checkpoint across two consecutive epochs, that checkpoint becomes finalized. Finalized blocks cannot be reorganized without slashing at least 1/3 of all validators.

Attestation Timing

Validators must submit attestations within a specific time window. The attestation slot is assigned pseudorandomly each epoch. Missing your slot means missing rewards for that attestation.

Impact on Staking Returns

Attestation performance directly affects staking APY. Validators with perfect attestation records earn more than those with missed or delayed attestations. This is why validator uptime and client performance matter significantly.