Validator

A validator is a participant in a proof-of-stake blockchain who locks up (stakes) the network's cryptocurrency for the right to propose and attest to new blocks, earning rewards for honest work and risking penalties for misbehavior. Where proof-of-work miners compete with electricity and hardware, validators are chosen — usually pseudo-randomly, weighted by stake — to take turns producing blocks and voting on which chain is correct.

The economic design is what keeps validators honest. Rewards accrue for timely, correct participation, while provable cheating, such as signing two conflicting blocks, can trigger slashing: the destruction of part of the validator's staked coins. For example, running an Ethereum validator requires depositing 32 ETH and keeping software online; an operator who double-signs can be slashed and forcibly ejected, while one who merely goes offline suffers small, gradual penalties.

A common misconception is that validators can steal funds or alter balances; they can only order and include valid transactions, because blocks that break the rules are rejected by the network's full nodes regardless of who signed them. Because running a validator takes technical effort and, on some chains, a large minimum stake, many holders instead delegate to staking services or pools, which introduces its own trade-off: convenience in exchange for concentrating influence in a smaller number of large operators.