A node is a computer that participates in a network, helping to validate and relay transactions. In the context of blockchain, nodes maintain a copy of the entire blockchain or a segment of it. They play a crucial role in ensuring the network’s security, reliability, and integrity.There are different types of nodes. Full nodes store the complete history of the blockchain and verify transactions and blocks. They contribute to network consensus by enforcing rules and rejecting invalid transactions.Light nodes, on the other hand, do not store the entire blockchain. Instead, they rely on full nodes to get information, making them faster and less resource-intensive but dependent on full nodes for security.Nodes collectively help in maintaining decentralization, as they are spread across various locations and operated by different individuals or entities. This distribution makes it difficult for any single party to exert control over the network. Overall, nodes are fundamental to the functioning and health of a blockchain system.