The network

The Bitcoin network is a group of computers that run the same Bitcoin software and connect to each other directly. No company or central server runs it. Each computer passes new transactions and blocks on to the others, so every copy of the record stays up to date.

This page is part of the beginners guide. It explains how news travels across the network. The next page explains what each computer does on it.

What does the network do?

The computers on the network talk to each other all the time. They send messages about what is happening, such as a new payment or a new block. The software on each computer is called a client, and clients send these messages to one another.

Say you send a bitcoin payment from your wallet. Your wallet sends it to one computer. That computer tells its neighbors about it. Each neighbor checks the payment, then tells its own neighbors. The news keeps moving until most of the network has it.

This sharing keeps everyone in step. Without it, each computer would see a different set of payments, and nobody could agree on what had happened. The news has to travel, so that everyone reaches the same picture of who paid whom.

How is the network organized?

The network is peer-to-peer, or P2P. Each computer is a peer, and every peer has the same standing as the others. Nobody is in charge, and nobody can give orders to the rest.

Each computer links to a handful of others, and those link to still more. The links form a web, with no center. The Bitcoin developer guide describes this design in more detail.

Because there is no center, the network keeps working when one computer goes offline. Messages take another route to reach the computers that need them.

Who can join the network?

Anyone can join. You need an internet connection and the Bitcoin software. You do not need permission, an account or a fee.

The main software is Bitcoin Core. It is free and open source, so anyone can read its code. When you start it, your computer connects to other computers and becomes one of them. The node page explains what that means.

Why does the network matter?

No single company decides which payments are valid. Instead, many independent computers check each payment against the same rules, and each one reaches its own verdict. This is what people mean by decentralized. The more nodes there are, and the more places they run, the harder it is for one party to control what the network accepts.

Can I see the network on Explore21?

Our explorer reads everything from our own Bitcoin node. It shows what that node has received and checked. The latest blocks page lists each new block as our node receives it. Every one of those blocks crossed the network to reach us.

For a look further back, open block 0, the first block ever mined. It has been part of the record since 3 January 2009.

What should you read next?

The next page is the node. It covers the three jobs a node does, and why each job matters to the whole network.