A Block Validator is a participant in a blockchain network responsible for verifying and confirming transactions. Their main role is to ensure that the information contained in a block is accurate and adheres to the network’s rules before it gets added to the blockchain.

Validators achieve this by performing checks on the transactions in the block, validating digital signatures, and ensuring there’s no double-spending. Once a block is confirmed, it becomes part of the immutable record of transactions.

In some networks, validators are chosen based on their stake in the system, where users must lock up a certain amount of tokens as collateral. This process, known as Proof of Stake, incentivizes honest behavior since malicious actions could lead to losing their staked assets.

In others, validators compete to solve complex mathematical problems (Proof of Work) to add a new block. The role of a validator is crucial for maintaining the integrity, security, and efficiency of the network.