Coinbase

The coinbase is the content of the 'input' of a generation transaction. While regular transactions use the 'inputs' section to refer to their parent transaction outputs, a generation transaction has no parent, and creates new coins from nothing.

For the business, see Coinbase (business).

The coinbase can contain any arbitrary data. The genesis block famously contains the dated title of a newspaper article in The Times:

The Times 03/Jan/2009 Chancellor on brink of second bailout for banks