A node is any computer running Bitcoin software, most commonly Bitcoin Core. Nodes are the real enforcers of Bitcoin's rules.
What a node does
A full node downloads every block since 2009 and checks every rule itself: valid signatures, no double spending, correct block reward, the 21 million cap. It relays valid transactions and blocks to its peers and rejects anything invalid — even from a powerful miner.
Miners propose, nodes decide
Miners produce blocks, but a block breaking the rules is simply ignored by nodes, wasting the miner's energy. This balance is why no single group can change Bitcoin unilaterally.
Why run one?
- Verify, don't trust: you confirm your own payments.
- Privacy: your wallet doesn't leak addresses to third parties.
- Voice: you choose which rules you follow.
Requirements
A full node needs several hundred gigabytes of storage (the chain was about 780 GB as of October 2026) and a steady connection, but runs fine on a small home computer. Pruned nodes discard old blocks after verifying them to save space.
Crawlers such as Bitnodes count roughly 20,000 reachable public nodes at a time, and many more nodes do not accept incoming connections and cannot be counted directly.