What is a Bitcoin Node?
A computer running Bitcoin software that maintains a full or partial copy of the blockchain. Full nodes download and validate every transaction and block according to Bitcoin's rules.
Why It Matters
Nodes are what make Bitcoin decentralized. Anyone can run a node—it requires a computer and over 600 GB of storage to download the entire blockchain. By running a node, you can independently verify that the bitcoin you receive is legitimate without trusting anyone else. Nodes validate that miners aren't breaking Bitcoin's rules, that the money supply doesn't exceed 21 million, and that transactions follow proper format. If miners tried to create invalid blocks, your node would reject them. This is crucial because it means Bitcoin doesn't depend on trusting mining pools, exchanges, or anyone else. There are thousands of nodes worldwide, making centralized control impossible. You don't need to run a node to use Bitcoin, but running one maximizes your sovereignty.
How It Works
A full node downloads the entire blockchain from the Genesis Block to the current block height, validating every transaction and block according to Bitcoin's consensus rules. Nodes relay transactions to other nodes, creating the peer-to-peer network. When a new block is mined, nodes receive it, validate it, and if valid, add it to their local copy of the blockchain. Nodes use the blockchain to verify that transactions don't double-spend and that senders actually own the bitcoin they're moving. If you run a full node and someone tries to send you counterfeit bitcoin or invalid transactions, your node rejects them. Light clients and wallets can connect to full nodes to verify transactions without maintaining the entire blockchain themselves.