Node
A computer that participates in a blockchain network by storing and relaying data.
A node is any device that connects to a blockchain network to store a copy of the ledger, validate transactions, and relay data to other nodes. The aggregate of all nodes forms the decentralised network that makes a public blockchain censorship-resistant.
Full nodes download and independently verify the entire blockchain history. Light nodes (SPV nodes) only download block headers and rely on full nodes for transaction verification. Archival nodes retain the complete state at every block height, which is essential for querying historical data.
Running a full node is considered a civic duty in Bitcoin culture because it enforces the network's rules independently, without trusting miners or third-party services.