Bitcoin's Fixed Supply: 21 Million

There will only ever be 21 million Bitcoin. This hard cap is enforced by the protocol itself and cannot be changed without consensus from the entire network. Every four years, the block reward (new Bitcoin created per block) is cut in half in an event called the "halving." This predictable, decreasing supply schedule is what gives Bitcoin its "digital gold" narrative and distinguishes it from fiat currencies, which can be printed without limit.