A coinbase transaction or generation transaction is always created by a miner and is the first transaction in a block. It is used to create new coins. It includes a special field, also called coinbase, which acts as an input to the coinbase transaction. This transaction also allows up to 100 bytes of arbitrary data that can be used to store arbitrary data. In the genesis block, this transaction included the most famous comment taken from The Times newspaper:
This message is a proof that the genesis block was not mined earlier than January 3, 2009. This is because first Bitcoin block (genesis block) was created on January 3, 2009 and this news excerpt ...