Bitcoin Node

When a new transaction or block appears, a full node checks it against Bitcoin's rules: valid signatures, no double-spending, correct block structure, proper difficulty, and more. If valid, the node stores it and relays it to peers; if invalid, it rejects it. Because each node applies the same rules independently, the network reaches consensus without a central authority.

Some nodes also mine (producing new blocks), but most full nodes simply validate and relay. Lightweight wallets do not keep the full chain—they rely on full nodes for verification. The more independent full nodes exist, the harder it is for any party to change the rules or censor transactions.

Nodes are the enforcement layer of Bitcoin. Exchanges and miners can propose changes, but rules only actually change if the economic majority of running nodes accepts them. Running your own node means you do not have to trust an exchange or block explorer to tell you the truth—you verify it yourself. This is the practical meaning of 'be your own bank.'

A business that receives large Bitcoin payments runs its own full node. When a customer pays, the business's node checks the transaction directly against the blockchain rather than trusting a third-party service. This means the business cannot be fooled by a fake confirmation shown on someone else's website.

Many people think miners alone run Bitcoin. Miners produce new blocks, but full nodes decide which blocks are valid in the first place. A miner could produce a block that breaks the rules, but every full node would reject it instantly. Nodes and miners have separate, complementary roles.