A blockchain is not kept in one place. It lives across thousands of machines that each run the network's software, and every one of those machines is a node. Nodes receive newly-broadcast transactions and blocks, independently check them against the rules, and relay onward only the ones that pass. A so-called full node keeps the entire history and verifies everything for itself, which means it never has to take anyone else's word for what is valid.
This is the practical backbone of decentralisation. Because many independent nodes each hold the ledger and enforce the same rules, no single company can quietly rewrite history or slip in a fake transaction; the other nodes would simply reject anything that breaks the rules. If a large share of the network went offline, the chain would carry on running on whatever nodes remained, which is why there is no single switch to flip to shut it down.
Not every node does the same job. Some also mine or validate and therefore help produce new blocks, while many simply verify and pass along data. Running your own node is the most trust-minimised way to use a blockchain: instead of relying on someone else's server to tell you your balance, you check every rule yourself. For most users this happens invisibly behind a wallet, but it is what the whole system rests on.
Key takeaways
- A node is a computer running a blockchain's software and holding a copy of the ledger.
- Full nodes independently verify every transaction and block, so they never have to trust another party's data.
- The spread of many independent nodes is what makes a blockchain hard for any single actor to control or shut down.
Node — perguntas frequentes
Is every node also a miner or validator?
No. Every miner or validator runs a node, but the majority of nodes do neither. A plain node verifies and relays transactions and blocks, while mining and validating are additional roles that also produce new blocks.
What is the point of running my own node?
It lets you use a blockchain without trusting a third party. Your own full node checks every rule itself, so you can verify your balance and transactions directly rather than relying on an external service to report them accurately.
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