The Bitcoin halving, explained without the hype
Every 210,000 blocks the reward miners receive is cut in half. Here is what that mechanism does, and what it does not do.
Bitcoin issues new coins as a reward to the miners who add blocks to the chain. The protocol halves that reward roughly every four years, at fixed block heights. The rule is written into the software, so no company or committee decides when it happens.
Because issuance shrinks over time, the total supply approaches a ceiling of 21 million coins. That predictable schedule is one of the most cited features of Bitcoin, and it is often contrasted with currencies whose supply can be expanded at will.
A halving changes the economics for miners. Their revenue per block drops overnight, so less efficient operations can become unprofitable. The network adjusts mining difficulty every 2,016 blocks, which keeps block times close to ten minutes even when miners leave.
What a halving does not guarantee is a price movement. Markets have reacted very differently around past halvings, and many other factors move prices at the same time. Treat any claim that a halving 'always' leads to a rally with caution.