Glossary
Halving
Bitcoin's programmed event, every 210,000 blocks (~4 years), that cuts the per-block subsidy in half — converging toward the 21-million-BTC cap.
Every 210,000 blocks — roughly every four years — Bitcoin's per-block subsidy is cut in half: 50 → 25 → 12.5 → 6.25 → 3.125 BTC and so on. The schedule converges to a hard cap of 21 million BTC some time after the year 2140.
Halvings are watched closely by markets because they roughly halve the rate at which new supply hits the market while ongoing demand, in theory, stays the same. Most other PoW chains adopt a similar schedule, with different intervals and starting subsidies.