Bitcoin halving is a process of dividing the number of generated rewards per block in order to maintain the total supply of Bitcoin, which will not exceed 21 million. Block rewards are the main engine of Bitcoin mining and, therefore, the main power behind the operation of the network. Bitcoin halving happens every 210,000 blocks and reduces the reward for 50 percent every time in a geometrical progression. The initial block reward in 2009 was 50 Bitcoins, the current Bitcoin reward is 12.5 coins and the process is expected to end in 2024 with all Bitcoins being issued. The next Bitcoin halving is expected to happen in May 2020 and will decrease the reward to 6.25 coins. Bitcoin halving is a crucial part of Bitcoin and most other cryptocurrencies, as it is the main algorithm of emission control and a part of what makes Bitcoin successfully maintained without any authority.