Overview
A node is a computer that participates in a blockchain network by storing data, validating transactions, and relaying information to other participants. Full nodes maintain a complete copy of the blockchain ledger and independently verify every transaction and block against the network's rules. Light nodes download only block headers and rely on full nodes for transaction data.
How It Works
When a new block is produced, nodes validate its transactions and signatures, check that it follows the consensus rules, and propagate it to their peers. This peer-to-peer relaying keeps the network synchronized. A full node can reject invalid blocks even if the rest of the network accepts them, which is what makes a network's rules enforceable without trust. Running a full node is the way to get the highest level of self-sovereignty on a network.
Why It Matters
Nodes are the backbone of decentralization. The more independent full nodes a network has, the harder it is for any party to censor or manipulate the ledger. For individuals, running a node provides privacy, trustless verification, and resilience against service outages. For developers, nodes are the interface through which applications query state and broadcast transactions.
Related Concepts
Nodes form the peer network that Consensus mechanisms coordinate. Miners and Validators are specialized node operators, and Wallets and explorers read blockchain state through nodes.