2.9 Why Run a Node?

A 'node' is just a computer running Bitcoin software that keeps a full copy of the entire ledger and personally double-checks every new block and transaction against the rules. It's basically your own private auditor.

If you don't run a node, you're trusting someone else — an exchange, a block explorer, a wallet server — to tell you what's true. They might be honest, but you have no way to verify on your own.

Here's the surprising part: nodes, not miners, are actually in charge of Bitcoin. Miners propose blocks, but every node decides whether to accept them. If miners ever tried to change the rules — for example, by printing extra coins — the nodes would simply reject those blocks as invalid.

This is exactly what happened during past attempts to change Bitcoin (the 2017 'block size war' is the famous one). Users running their own nodes refused the change, and that was the end of it.

Running a node is also great for privacy: your wallet asks your own computer about your balance instead of telling a third party which addresses to look up.