What is beacon chain?

Ethereum's consensus layer, which tracks validators, assigns block proposals, and finalizes the chain.

It launched in December 2020 alongside proof-of-work and took over consensus at the Merge in September 2022 (source: the Ethereum consensus specifications). A validator activates by depositing 32 ETH and then attests to what it sees each epoch; the execution layer handles transactions and state while the beacon chain decides which chain is canonical.

Consensus and execution now run as two separate programs on every node, joined by a local interface, which is why operators talk about running a client pair. Most buyers meet the beacon chain indirectly, through a staking product whose yield comes from the rewards it pays.

How it works

Time on the beacon chain is divided into slots and epochs. A single validator is chosen as block proposer for each slot, and the rest are organized into committees that attest to what they saw.

An attestation is a validator's signed vote on the head of the chain and on the checkpoints it considers justified. Aggregating those votes is how the network agrees without anyone being in charge.

Finality comes from checkpoint voting. When a supermajority of stake attests across two consecutive epoch boundaries, the earlier checkpoint is finalized, meaning reverting it would require destroying an enormous amount of staked value. This is a stronger guarantee than proof-of-work's probabilistic settlement.

Validators earn for attesting correctly and promptly, and lose small amounts for being offline. Provably malicious behavior, such as signing two conflicting blocks, triggers slashing, which removes a portion of the stake and ejects the validator.

Withdrawals from staking are enabled through withdrawal credentials set on the validator, with exits processed through a rate-limited queue rather than immediately.

Example

Illustrative: an exchange staking product pools customer deposits into validators of 32 ETH each. You deposit 1 ETH and own a fractional claim. The validators earn attestation rewards each epoch plus occasional proposal rewards, the exchange takes a commission, and the remainder is credited to you. When you unstake, the exchange either sells your claim to another customer immediately or joins the exit queue, which is why some venues pay out in minutes and others in days.

Why it matters when you buy

If you buy ether and use any staking product, the beacon chain is what generates the yield and what sets the limits on getting your principal back. The exit queue, not the exchange's marketing, determines the worst case on timing. Compare staking terms across venues at the exchange directory, and read the staking guide before locking anything up.

Related terms

• validator — the staked participant that votes
• proof of stake — the consensus model it implements
• epoch — the period over which votes are counted
• slot — the interval in which one block is proposed
• the merge — when it took over consensus
• slashing — the penalty for provable misbehavior

Questions

Do I need 32 ETH to stake?

To run your own validator, yes. Pooled and liquid staking products let you stake any amount by aggregating deposits, at the cost of trusting the operator.

What is the difference between the beacon chain and Ethereum?

The beacon chain is Ethereum's consensus layer. The execution layer processes transactions and holds account state. Both run together on every node and neither is a separate network.

How long does unstaking take?

It depends on the exit queue, which lengthens when many validators leave at once. Some platforms mask the wait by matching you against incoming deposits; the underlying queue is still the limit.