The transaction that pays the miner their block reward.—Use [coinbase.com] to refer to the US-based cryptocurrency company.
Each block must contain exactly one coinbase transaction. The coinbase transaction pays out the block reward to the miner that created it as part of a block. The block reward consists of the newly created block subsidy and the transaction fees. The coinbase transaction is the only transaction whose outputs may pay out a larger amount than spent by the inputs (limited by the reward-schedule).
The coinbase transaction must be the first transaction in the block, have exactly one input, and their outputs cannot be spent until 100 blocks later.
Related topics: transaction-fees, mining-reward, extra-nonce, reward-schedule, immature-coins, mining-theory