fullnodes

Full nodes are network participants that maintain a complete copy of the blockchain and enforce the protocol’s rules. In most blockchain networks, a full node validates every block and transaction, stores the entire history, and relays data to other nodes to help maintain consensus.

Operation: They verify blocks and transactions against consensus rules, enforce the current state, check signatures, and update their local copy. They typically expose interfaces (APIs or RPC) that wallets and other services use to query blockchain data or submit transactions.

Types: Archival full nodes keep the entire historical data and state; pruned full nodes store only a recent window of data while still validating new blocks. Some networks also support light clients or SPV nodes that download only block headers and rely on full nodes for full validation.

Requirements and trade-offs: Running a full node requires storage, bandwidth, and processing power; the exact needs depend on the network and whether the node is archival or pruned. The initial sync can be lengthy. Pruned nodes reduce storage at the cost of not being able to serve old data; archival nodes provide complete historical data at higher resource needs.

Role: Full nodes contribute to security, censorship resistance, and decentralization by not relying on trusted third parties. They also enable wallets and services to operate in a trust-minimized way. Common implementations include Bitcoin Core, Ethereum clients such as Geth or Besu, and similar software for other networks.