Who Runs Bitcoin?

In May 2017, just before a major industry conference in New York, dozens of Bitcoin companies signed an agreement about Bitcoin's future. The signers included exchanges, payment firms and some of the largest mining pools. The plan had two stages: first activate an upgrade called SegWit, then, three months later, change the rules to double how much a Bitcoin block could hold.¹ By June, miners with more than 80 percent of the network's mining power were stamping their support into the blocks they produced.¹

By any normal measure it was going to happen. When the companies that handle most of an industry's customers and the businesses that do most of its work agree on a change, the change happens. That is how it works almost everywhere else.

On November 8, 2017, about a week before the second stage was due, the organizers called it off. In an email to the project's mailing list, they wrote that "we have not built sufficient consensus for a clean blocksize upgrade at this time."² If the companies and miners with that much weight could not change Bitcoin's rules, who can?

No Head Office

Go looking for the company behind Bitcoin and you will not find one. There is no headquarters, no CEO and no customer service number. Even its creator, known only by the pen name Satoshi Nakamoto, stepped away more than fifteen years ago; the last of Satoshi's forum posts is dated December 2010.³ Yet Bitcoin has kept running since January 2009, adding a new block about every ten minutes, through crashes, bans, bugs and the departure of the one person who started it.

Something is keeping it going. The answer is not one group but three, each with real power and none with all of it.

Anyone Can Check

Bitcoin is software, and it is free. Anyone can download it and run it on an ordinary computer, and a computer running it is called a node. A node does something unusual: it checks every block ever made, starting with the very first, and then checks every new block and every new transaction against Bitcoin's rules, for itself. It does not ask anyone whether a payment is valid. It does not take anyone's word for it.

No node is in charge of any other. A node in a data center and a node in someone's living room check exactly the same rules, and each one answers only to the person running it. One public count could see about 23,000 nodes at the end of October 2026, and many more run quietly behind home routers, where no count can reach them.⁴

Miners Build, Nodes Check

Miners are the ones racing to add the next block to the chain. They choose which waiting transactions go into their block and in what order, and that is real power: a miner can leave a transaction out or put it first. But a miner only proposes a block. Every node checks it, and if it breaks a rule, for instance by paying the miner more new bitcoin than the rules allow, every node throws it out, and the electricity spent finding it is wasted.⁵ Miners build the blocks. They do not decide the rules those blocks must follow.

Code Anyone Can Read, Nobody Can Force

The rules are written in code, and the code is written in the open by developers around the world. The best-known version is Bitcoin Core. Its version 31, released in April 2026, credited 101 people who contributed to it directly.⁶ Anyone can read every line, and anyone can propose a change.⁷

But nobody can push a new version onto your computer. Bitcoin Core does not update itself; every release comes with instructions for upgrading by hand, and each person running a node decides if and when to install it.⁶ That is why the same October 2026 count found hundreds of different software versions in use, some of them years old.⁴ A developer can write a new rule. It only becomes part of Bitcoin if enough of the people running Bitcoin choose to run it.

Why the Agreement Failed

That is what the signers of 2017 ran into. The first stage, SegWit, was a change older software could live with, and it activated that August. The second stage was different. Blocks made under the new, larger limit would be rejected by every node still running the old rules, and a great many people running nodes, along with a number of businesses, made clear that they would keep the old rules.⁸ Miners could have produced the bigger blocks. They could not make anyone else's node accept them. The result would not have been a changed Bitcoin, but a split one, with the signers on a chain of their own.

That had already happened once that year. In August 2017 a group that wanted bigger blocks went ahead on their own and started a separate chain, which still exists today as a different coin, Bitcoin Cash.⁹ Anyone is free to do that. What no one can do is take the rest of the network with them.

So who runs Bitcoin? No one does it alone. Developers propose. Miners build. Nodes check. Companies, miners and developers all have a voice, and some have a loud one. None of them can make your node accept a rule you do not run.

The white paper itself hints at why an ordinary business would bother. It notes that businesses receiving frequent payments "will probably still want to run their own nodes," for security they do not have to take on trust.¹⁰ A rule that only counts when people choose to run it is a rule no single company can change on them.

Lesson 4 of the course looks at nodes and miners in more detail, including who actually enforces the rules. How that differs from coins that do have a company or founder in charge is the subject of Lesson 9. What makes any money trustworthy in the first place is where the free first lesson begins.