A validator is a node in a proof-of-stake network that participates in consensus by validating transactions, proposing new blocks, and attesting to the validity of other blocks.
Validator responsibilities: Run node software continuously, stake required tokens, validate transactions, propose and attest to blocks, and maintain uptime for rewards.
Validator requirements: Minimum stake (32 ETH for Ethereum), reliable hardware and internet, technical knowledge, and security practices.
Validator economics: Earn rewards for honest participation, face slashing for misbehavior or downtime, and must balance rewards against operational costs.