Block 0 · 3 January 2009
The genesis block
Every Bitcoin node in the world starts from this block. Its data is written into the software itself, so that each node begins its copy of the chain from the same point.
Satoshi Nakamoto mined it on 3 January 2009, two months after publishing the white paper that described the system. The block carries a single transaction, the one that creates its reward, and in the data of that transaction a line of text: the headline of The Times of London that morning, “Chancellor on brink of second bailout for banks”. The headline dates the block, since it could not have been written before that day, and it is hard not to read it as a comment on the banking crisis Bitcoin was answering.
The reward of the genesis block, 50 bitcoins, cannot be spent. The software never added that first output to the coins it keeps track of, and it has stayed that way ever since.
Block 1 followed on 9 January 2009, hours after Satoshi announced the first version of the software on the Cryptography mailing list. From then on, each new block has named the one before it, all the way back to this one.
On the poster, the box of the previous block stays empty: nothing comes before the genesis block.