Glossary
Beacon Chain
Ethereum's proof-of-stake consensus layer — coordinates validators, schedules block proposers, accumulates attestations, and decides finality.
The beacon chain launched in December 2020 as a parallel PoS chain that ran alongside the original Ethereum PoW chain. At the Merge in September 2022, it became Ethereum's sole consensus layer — every block is now proposed by a randomly selected beacon-chain validator.
The beacon chain tracks validator stakes, rotates committee assignments per slot and epoch, aggregates BLS attestations, and finalizes checkpoints once two-thirds of stake agree across two consecutive epochs.