What Is the Genesis Block? The First Block of Bitcoin

The genesis block is the first block of the Bitcoin blockchain, created on 3 January 2009. Every bitcoin transaction ever made sits on a chain that leads back to it. It is the only block that was not built on top of an earlier one, because when it was made there was nothing earlier.

Why the first block is different

A blockchain is a chain because each block carries a pointer to the one before it, the way pages in a shared notebook are numbered in order. Pick any block from today, follow those pointers backwards, and you land hundreds of thousands of steps later in the same place. The genesis block has nothing to point at, so it was written straight into Bitcoin's software rather than mined the usual way. Every copy of that software, on every computer running Bitcoin, starts from the identical block zero. That is what stops two people from disagreeing about where the record begins.

The message hidden inside it

Whoever built the block left a line of text in it: the front-page headline of a London newspaper printed that same day, about banks needing a second bailout. It was a neat trick. Nobody could have written that sentence before the paper came out, so the line proves the block is not older than 3 January 2009. It also says something about the timing, which was rather the point.

The 50 coins nobody can spend

Mining the genesis block paid a reward of 50 BTC, the going rate then. Because of a quirk in the original code, that particular reward can never be moved. The coins sit at their address permanently, visible to everyone and spendable by no one. People still send tiny amounts of bitcoin to that address as a kind of tribute, and those get stuck there too.

Go and look at it

None of this needs to be taken on trust. Any block explorer, a free website that lets you read the blockchain like a public database, will show you block 0: its date, its reward, its buried headline. Searching for "bitcoin block 0" is enough to find it. If the idea of a public record anyone can audit is new to you, start with how the shared ledger works, then what Bitcoin is.