Bitcoin halving is an event that occurs approximately every four years as part of the Bitcoin protocol. During a halving event, the reward for miners who successfully validate new transactions on the Bitcoin blockchain is reduced by half. This means that the amount of new bitcoins created and rewarded to miners for each block mined is reduced by half, which in turn reduces the rate at which new bitcoins are introduced into circulation.

The first Bitcoin halving took place in 2012 when the reward was reduced from 50 bitcoins per block to 25 bitcoins per block. The second halving occurred in 2016 when the reward was reduced from 25 bitcoins per block to 12.5 bitcoins per block. The most recent halving event took place on May 11, 2020, and the reward was reduced from 12.5 bitcoins per block to 6.25 bitcoins per block.

Bitcoin halving is designed to control the inflation rate of Bitcoin by gradually decreasing the supply of new bitcoins over time. This is intended to ensure that there will never be more than 21 million bitcoins in circulation, which is the maximum number of bitcoins that can ever exist according to the Bitcoin protocol. As the supply of new bitcoins decreases, the theory is that the demand for them will increase, potentially leading to an increase in the price of Bitcoin