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Concept
Economics
The 21 Million Cap
First appeared Jan 2009
Why it matters
A fixed, predictable, diminishing supply is Bitcoin's answer to monetary debasement — the property advocates call "digital scarcity" and "hard money."
What it is
Bitcoin's total supply is capped at ~21 million coins, issued on a geometric schedule that halves the block reward roughly every four years (every 210,000 blocks).