Halving

The halving is a scheduled event, every 210,000 blocks (roughly four years), where the block subsidy — the new bitcoin paid to miners per block — is cut in half. It started at 50 BTC in 2009 and has halved at each event since; the schedule continues until issuance reaches zero around 2140.

Halvings are how the 21 million cap is implemented in time: predictable, verifiable, and immune to lobbying. No committee can accelerate or postpone one.