THC, or delta-9-tetrahydrocannabinol, is a terpenophenolic compound derived from cannabis. It is the main psychoactive component of cannabis, and is produced in glandular trichomes, particularly in the unfertilized female flowering tops of the plant. THC is an extremely sticky liquid at room temperature. It boils at 157 degrees Celsius, which allows its use by smoking or vaporization. THC is not water soluble, but is easily dissolved in lipids or alcohol.

THC possesses analgesic (pain relieving), anti-inflammatory, anti-emetic (nausea-preventing), antioxidant, and euphoric effects.

THC in cannabis, or naturally extracted THC, is classified as Schedule I by the DEA, implying that it is dangerous and has no accepted medical use, not withstanding its known pharmaceutical applications.