THCA is tetrahydrocannabinolic acid, the acidic compound the living hemp plant actually produces. In its raw state it is not intoxicating. Applying heat converts it, which is why THCA products are sold raw and measured raw.

That distinction is what makes these products federally compliant hemp: measured by Delta-9 THC on a dry weight basis, they sit under the 0.3% threshold set by the 2018 Farm Bill. It is also why state law matters so much, several states regulate THCA separately from the federal standard.