The short answer
A node is a computer running Bitcoin software that keeps its own copy of the ledger and checks every transaction and every block against the rules itself, rather than believing what it is told.
Nodes are not paid. They do not compete, they do not vote, and they produce nothing. What they do is refuse. A block that breaks a rule is dropped, and nothing further is relayed from it, no matter who mined it or how much work went into it.
That is the whole role, and it is the reason miners cannot simply decide to pay themselves more.
What a node actually checks
When a block arrives, a node verifies it from scratch. Among other things:
- Every signature on every transaction is valid for the coins being spent.
- Every input refers to an output that exists and has not already been spent.
- The block's proof of work meets the current difficulty target.
- The block's header links to a block the node already has.
- The subsidy the miner paid itself matches the issuance schedule exactly.
None of this involves asking anybody. The node has the rules and the history, so it can answer for itself. That is the difference between verifying and trusting, and the phrase people repeat, "don't trust, verify", refers to precisely this and to nothing more romantic.
What a node cannot do
This is where the mental model usually goes wrong.
A node cannot force any other node to agree with it. It cannot block a transaction that other nodes accept, or vote a change into existence. If your node has different rules from everybody else's, the result is not influence: it is that you are now tracking a different chain, alone.
A node also earns nothing and never will. There is no reward, no yield, and nothing to stake. Anyone offering you one has misunderstood or is selling something.
Full, pruned, and light
A full node downloads every block ever mined, validates all of it, and keeps it. Validating the entire chain from the genesis block is the initial block download, and it takes hours to days depending on the machine.
A pruned node does exactly the same validation and then deletes old block data it no longer needs, keeping the set of unspent outputs and a recent window of blocks. It is worth being blunt about this, because the old advice on this page and on most others is wrong: a pruned node is a fully validating node. It checked everything. The only thing it gives up is the ability to serve historical blocks to other peers, and to rescan for an old wallet without re-downloading.
A light wallet (often called SPV, for simplified payment verification) stores no chain at all. It asks a server whether a transaction is confirmed and believes the answer. Most phone wallets work this way, which is a reasonable trade for spending money, and two things come with it: the server can lie to you about the state of the chain, and it learns which addresses are yours.
Miners run full nodes too. "Mining node" is not a separate category so much as a full node with hardware attached to it.
What it costs to run one
As of August 2026, Bitcoin Core is at version 31.1 and its own download page asks for roughly 600 GB of disk plus another 5 to 10 GB a month, or as little as around 10 GB if you enable pruning. It also wants a connection that can upload steadily, since your node serves blocks to peers.
Set prune=550 or higher in the configuration file and the disk requirement stops being the
obstacle people assume it is. A second-hand laptop or a small single-board computer is
enough.
The real cost is not the hardware. It is that a node is a service you now operate: it needs to stay online to be useful, it needs its software updated, and if you point your wallet at it, your wallet stops working when it does.
What you get out of it
Three things, and they are worth stating plainly rather than as a slogan.
You stop asking. With a wallet connected to your own node, "did that payment arrive" is answered by software you control against rules you chose to run. No third party is in the loop to be wrong, compromised, or subpoenaed.
Your privacy improves substantially. A light wallet tells some company every address you own. Your own node tells nobody, because it holds the whole chain and looks locally.
Your view of the rules counts. If a change is proposed that you do not accept, running a node is the difference between having an opinion and enforcing one. Not because your node outvotes anyone, but because a rule change only takes effect if the nodes that people actually use accept it.
What people get wrong
"There are N nodes on the network." Nobody knows the number. The counts that circulate come from crawlers that can only see nodes accepting incoming connections, and a large share of nodes sit behind a home router or Tor and never accept any. Every published figure is a floor, not a count.
"Running a node earns bitcoin." It does not. See above.
"You need a terabyte drive." You need about 10 GB with pruning on. This one has probably put off more people than any other sentence about nodes.
"A node validates transactions for other people." It validates them for itself, and relays what passes. The benefit to everyone else is a side effect of a lot of people each checking selfishly.
Where to go next
If you have followed the series this far, the pieces are in place: keys sign, nodes check, miners order, and the chain records. The step after understanding is doing, which starts with how to choose a wallet.