TL;DR
Token supply refers to the number of tokens in existence, broken down into circulating supply (freely tradeable), total supply (all minted tokens), and max supply (hard cap if one exists).
Circulating supply is the number of tokens actively available in the market — excludes locked, vesting, or burned tokens. Total supply is everything that’s been minted minus what’s been burned. Max supply is the hard cap (if one exists) — no more tokens can ever be created beyond this number. SOL has no max supply (it’s inflationary via staking rewards), while most memecoins have a fixed total supply.
Supply directly affects price. A token with 1 billion supply at $0.001 has the same market cap as a token with 1 million supply at $1 — but the first “looks cheap” to retail traders (unit bias). Projects manipulate supply numbers for psychological pricing. What actually matters is market cap and FDV, not the nominal token price or supply number.
For SPL tokens, supply data is stored directly in the mint account on-chain and can be verified using any block explorer. Check whether the mint authority is revoked — if it’s not, the creator can mint more tokens at any time, making the current supply meaningless as a cap. Token Scanner and security tools flag active mint authorities as a risk factor.