Definition
Block validation is a core blockchain process in which a proposed block is checked to ensure it complies with all consensus and protocol rules. During block validation, each transaction inside the block and the block’s structural data are examined by participating nodes. Only blocks that fully satisfy these rules are considered valid and eligible to be appended to the existing chain.
This process is performed independently by many nodes to maintain a consistent and trustworthy ledger. By rejecting invalid blocks, block validation prevents malformed data, double-spends, and other rule violations from entering the blockchain. It is a recurring, protocol-defined procedure that underpins the integrity and reliability of the entire network.
Context and Usage
In most blockchain systems, every node that receives a new block candidate runs its own block validation checks before relaying or accepting it. Validators in consensus roles focus on proposing and attesting to blocks, but their work still depends on correct block validation logic implemented across the network. This shared process ensures that all honest participants converge on the same valid chain of blocks.
Block validation is closely tied to the definition of a block and the consensus rules that govern which chain is considered canonical. When block validation is consistent across nodes, the network can reliably agree on the same transaction history without central coordination. As a result, block validation functions as a foundational security and correctness mechanism for decentralized ledgers.