Circulating Supply vs Total Supply
Circulating supply is the number of coins currently tradable; total supply includes coins that exist but are locked, and max supply is the hard cap that can ever exist.
In depth
A project may have a large total supply with most of it locked for the team or future rewards. As those unlock, circulating supply grows and can pressure the price. Bitcoin’s max supply is 21 million; some tokens have no cap at all.
Why it matters
Upcoming unlocks are one of the most predictable sources of selling pressure.