Coinbase (Mining reward)
Mining reward (coinbase) refers to the transaction whereby miners receive Bitcoin as a reward for generating a new block through mining.
Bitcoin is only issued through mining and, when it is newly issued, it is given to the successful miners as a reward.
The reward for mining a block began at 50 BTC. The reward is halved every 210,000 blocks, and the 6,929,999th block will be the last to reward mining. The total amount of Bitcoin to be issued is 21 million BTC -- the maximum amount of Bitcoin that can be issued.
Rewards decrease as explained above, and the speed at which it is issued is adjusted so that one block is generated every 10 minutes. It will take about 132 years to mine all 6,929,999 blocks, and the last block will be mined in 2140.