What Is Bitcoin?

Bitcoin is money that exists as entries in a ledger, and the ledger is kept by everyone at once instead of by a bank.

That sounds like a small change. It is not. Every other form of money you have used depends on an institution keeping the record: your bank knows your balance, and if its record says zero, you have zero. The record is the money. Whoever keeps it holds real power — to freeze an account, to reverse a payment, to refuse a customer, and to create more units.

Bitcoin removes that institution and replaces it with a rule everyone can check. Thousands of independent computers each keep a complete copy of the ledger, and each one verifies every rule for itself before accepting anything new. There is no head office to write to, no administrator with an override, and no way for anyone — including its own creator — to issue more than the schedule allows.

There are currently — blocks in that ledger, the first written on 3 January 2009, and every one of them is still checked by every node that starts up today.

Digital money was not a new idea in 2008. People had been trying since the 1980s, and every attempt hit the same wall.

A digital file can be copied perfectly. If money is a file, what stops you spending the same coin twice — sending it to one person, then sending the identical file to another? This is called the double-spending problem, and until 2008 there was only one known answer: appoint someone to keep the master list. A trusted third party who says which spend came first.

That answer works, and it is what banks and card networks do. But it puts the whole system back under one roof. Earlier digital-cash projects that tried it were shut down, went bankrupt, or simply never escaped the company that ran them.

The unsolved question was whether thousands of strangers, some of them actively dishonest, could agree on a single ordering of events with nobody in charge of deciding. Bitcoin's answer was to make agreement expensive: to add to the record you must spend real energy solving a puzzle with no shortcut, and the version of history with the most work behind it is the one everyone follows. Lying is not forbidden — it is simply made to cost more than it earns.

How proof of work does that, in detail

Nobody knows. That is the complete and honest answer, and this page is not going to improve on it.

What is known is narrow. The name appeared with the paper in 2008, communicated in writing for about two years, wrote a great deal of code and correspondence, and stopped. It may be one person or several. The writing suggests fluent English; the timing of posts has been analysed to death and proves nothing. Journalists have named candidates repeatedly; every case has rested on circumstance, and none has produced the one thing that would settle it.

That proof is simple and has never been provided: whoever controls the earliest coins can sign a message with those keys. It requires no interview, no documents and no trust. Several people have publicly claimed to be Satoshi. None has done it. In 2024 a London court examined the most persistent of those claims in detail and ruled against it.

Why it matters less than it seems. Bitcoin's rules are enforced by every participant independently. Satoshi returning tomorrow could not raise the 21 million cap, reverse a transaction or seize a coin — the software other people run would reject the attempt exactly as it rejects anyone else's. The author's identity is a genuinely fascinating mystery and an almost entirely irrelevant one.

Estimates of how much the earliest miner holds are published on our genesis page as a range, clearly separated from anything observed, because they are inferred from patterns in block headers rather than read from any address.