Node validation is the process by which nodes in a blockchain network verify the accuracy and authenticity of transactions and blocks before adding them to the blockchain. Each node maintains a copy of the entire blockchain and plays a critical role in ensuring that the network operates correctly.When a transaction is initiated, it is broadcast to the network. Nodes receive this transaction and validate it by checking various criteria, such as digital signatures, available balances, and adherence to consensus rules. If a transaction is deemed valid, it is included in a block for further processing.Once a block is created, it must also be validated by nodes. They check whether the block contains valid transactions and whether it follows the rules of the blockchain protocol. After validation, nodes propagate the validated block to other nodes, contributing to the overall security and integrity of the blockchain.This validation process helps prevent fraud, double-spending, and ensures that all participants have a consistent view of the transaction history.