Node

Nodes are what make bitcoin work without a company in the middle. Each one keeps its own copy of the ledger and applies the rules independently, accepting nothing on anyone's say-so: Bitnodes counted 22,992 reachable nodes on April 27, 2026, and the history they carry had grown past 759 GB by that August. If you have never run one, somebody else is telling you what you own.

How it works

A node does four jobs at once, and none of them involves mining.

It finds peers, usually by asking a handful of hardcoded DNS seeds for addresses, then opens connections on port 8333. Bitcoin Core keeps eight outbound full-relay connections plus two that carry blocks only, and accepts inbound peers up to a default ceiling of 125 in total. That deliberately small number of outbound links is a security choice: the fewer peers you choose, the more careful the software has to be about choosing them well.

It validates. Every block that arrives is checked against the consensus rules from scratch: the header hash must fall below the current target, the merkle root must match the transactions actually included, every signature must verify, no output may be spent twice, and the miner's reward must not exceed the subsidy plus the fees collected. Coins created by a block cannot be spent for another 100 blocks. A block that breaks any of this is dropped, and the peer that sent it may be disconnected.

It stores. The node maintains the block files themselves and, separately, the set of unspent outputs distilled from them, which is the working database used to answer whether a coin exists. An archival node keeps every block since 2009; a pruned one deletes old block files once it has finished with them and keeps validating exactly the same way.

It relays. Valid unconfirmed transactions go into the mempool and get forwarded to peers, which is how your withdrawal reaches a miner in the first place.

Notice what is absent. A node has no vote, earns no reward, and cannot make anyone do anything. Its only power is refusal: rules it rejects do not propagate through it, and software that nobody runs governs nothing.

Why this matters when you buy bitcoin

Every confirmation you have ever seen came from somebody else's node.

When an exchange marks your withdrawal as sent, when a phone wallet shows three green checkmarks, when a block explorer displays a transaction ID, you are reading a report from a server you do not control. Usually the report is accurate. The point of a node is that you stop needing it to be. Your own node answers the only question that matters, which is whether a payment to you exists in a chain with real work behind it, and it answers using data it verified itself.

Privacy is the other half, and it is the half people underestimate. A wallet that queries someone else's server hands over the full list of addresses it is watching, which is a complete picture of your holdings and your habits tied to your IP address. Point that same wallet at your own node and the leak stops. This is the cheapest privacy upgrade available to an ordinary holder, and it costs nothing after the hardware.

The hardware is modest and the honest numbers are worth knowing. A second-hand mini PC and a 2 TB solid state drive will do it, because the archive passed 759 GB in August 2026 and a 1 TB drive is already uncomfortable. Sync takes hours to a couple of days depending on the machine. If disk space is the obstacle, pruning brings the requirement down to a few gigabytes without weakening a single check.

None of this is a substitute for choosing where to buy. Our 231 country guides cover which platforms can legally serve you, and our exchange reviews cover what they charge to get coins out. A node has no customers and no accounts, so it changes nothing about that decision. What it changes is what happens after the coins arrive.

The six hours in March 2013 when nodes disagreed

On March 11, 2013 the bitcoin network split in two, and the cause was a difference between node versions rather than anything a miner did wrong.

Bitcoin Core 0.8.0 had replaced the Berkeley DB storage layer with LevelDB. Berkeley DB had an undocumented limit on the number of locks it would take while processing a block, and nobody had written that limit down as a consensus rule because nobody knew it was one. A miner running 0.8.0 produced block 225,430, which was unusually large in its number of inputs. Nodes on 0.8.0 accepted it. Nodes on 0.7 and earlier hit the lock limit and rejected it, then kept building their own chain.

For roughly six hours and 24 blocks there were two bitcoin networks with two transaction histories. The resolution was social: developers asked the large pools running 0.8.0 to downgrade to 0.7, deliberately abandoning the longer chain so that every node in the world could agree again. BIP50 is the post-mortem.

The lesson is the one that gets forgotten in arguments about who controls bitcoin. The miners had the hash power and gave it up, because a chain that most nodes refuse to accept is worth nothing to the people mining it.

Node vs lightweight client

A node checks the rules; a lightweight client asks somebody who does. That is the entire difference, and it is not a matter of degree. A full node can tell you that a block printed extra coins and reject it. A lightweight client sees a header with valid work on it, sees a merkle branch, and reports the payment as confirmed, because checking anything more would require data it never downloaded. The phone in your pocket is almost certainly running the second kind.

Node vs mining

A node validates blocks; a miner produces them, and the overwhelming majority of nodes do neither mining nor anything else profitable. Mining needs purpose-built hardware and cheap electricity, and it pays in block rewards. Running a node needs an old computer, costs a few dollars of power a year, and pays nothing at all. The confusion matters because it feeds the idea that miners set the rules. Miners choose which valid transactions to include and in what order. Nodes decide what "valid" means, and a miner who ignores them mines a chain that nobody will pay for.