The “sender” of a special transaction included in every new block (on some blockchains) that creates new tokens from nothing. These tokens are given as a reward to the miner that creates the new block, thereby increasing the total amount of tokens in circulation within the blockchain. Some blockchains use the coinbase only at block 0 and have 100% of their tokens already created when the blockchain is launched. (“Coinbase” should not to be confused with the cryptocurrency exchange from San Francisco of the same name.)