The theoretical market cap if all tokens — including locked, unvested, and yet-to-be-emitted — were in circulation at the current price.
FDV is always ≥ market cap. A large ratio of FDV to market cap signals significant future token unlocks or emissions that will dilute current holders. DePIN investors and operators track FDV/market-cap ratios to anticipate sell pressure from early investors or team vesting.