1. The Bitcoin halving is an event where mining rewards are cut in half. 2. The event takes place every four years, according to pre-set rules in Bitcoin's code.
B. A brief history
1. 2009 – Bitcoin mining rewards start at 50 BTC per block. 2. 2012 – The first Bitcoin halving reduces mining rewards to 25 BTC. 3. 2016 – In the second halving, mining rewards go down to 12.5 BTC. 4. 2020 – In the third halving, mining rewards drop to 6.25 BTC. 5. 2140 – The 64th and last halving occurs and no new Bitcoin are created.