Definition
A full node is a Bitcoin client that downloads every block and transaction, independently verifies them against the network's consensus rules, and stores the complete blockchain on disk. By validating from the genesis block onward, a full node never trusts a third party to tell it the state of the ledger — it enforces the rules itself. This is the foundation of self-custody and sovereignty: "don't trust, verify" is only literally true when you run your own node.
What a full node enforces
A full node rejects any block or transaction that breaks consensus — invalid signatures, double-spends, inflation beyond the block subsidy, or malformed scripts. It maintains the UTXO set (the database of all spendable coins) and relays valid transactions to peers. Crucially, a full node has no say in which block gets mined, but it has absolute veto over which blocks are valid. Economic full nodes are what ultimately keep miners honest.
Storage and bandwidth
As of 2025 a full archival node stores roughly 600–650 GB of block data plus an ~8 GB UTXO set, and the initial block download can take many hours over a typical connection. Pruned nodes (see below) validate identically but discard old blocks to save space. Running a node on cheap hardware like a Raspberry Pi or mini-PC is well within reach of a home Bitcoiner.
For sovereignty-minded setups, pair a node with private hardware in our self-hosting guidance, and see the related UTXO entry to understand what the node actually tracks.
In Simple Terms
A full node is a Bitcoin client that downloads every block and transaction, independently verifies them against the network’s consensus rules, and stores the complete…