The roughly four-yearly cut in half of the number of new bitcoin issued with each block. The most recent was in April 2024; the next is due around 2028.
Bitcoin's code halves the block reward about every 210,000 blocks, so new supply falls over time until the 21 million cap is reached around 2140.
Why it matters
Past halvings were followed by large bull markets within 12 to 18 months, which many investors attribute to the supply cut. With only a handful of cycles and much bigger markets today, the pattern is a history, not a rule.
