The upper limit of the total amount of bitcoin is set to 2 1 10,000 pieces. This upper limit is achieved through the underlying code of Bitcoin, which ensures that Bitcoin has a strong scarcity in economic attributes. Bitcoin is issued by means of mining rewards. Every time a piece is dug, a certain amount of bitcoin will be rewarded according to the reward rules.
The reward of new coins is decreasing, starting from the initial 50 bitcoins per block and halving every 2 10000 block until the final reward is less than 1 cluster (that is, one of 100 million bitcoins). This will be done 64 times, so that the total amount of bitcoin issued is about 2 1 10,000 pieces. This process is expected to end around 2 140, when no new bitcoin will be generated.