Every full node independently validates everything it receives. It holds the ledger, verifies signatures and balances, rejects anything that breaks consensus rules, and relays what passes to its peers. No node trusts another; each checks for itself, which is what makes the network resistant to a compromised participant.
This is also where the rules actually live. A change to the protocol only takes effect if node operators run software that implements it, so contentious upgrades are decided by what nodes choose to accept rather than announced from anywhere. Running one is the only way to verify the chain's state without taking a third party's word for it.
What is the difference between a node and a miner?
A node validates and relays; a miner also competes to produce new blocks. Every miner runs a node, but the great majority of nodes do no mining.
Last updated October 17, 2026