Cannabis is a natural product, the main psychoactive constituent of which is tetrahydrocannabinol (Δ9-THC). The cannabis plant (Cannabis sativa L.) is broadly distributed and grows in temperate and tropical areas. Together with tobacco, alcohol and caffeine, it is one of the most widely consumed drugs throughout the world, and has been used as a drug and a source of fibre since historical times. Herbal cannabis consists of the dried flowering tops and leaves.

Cannabis resin is a compressed solid made from the resinous parts of the plant, and cannabis (hash) oil is a solvent extract of cannabis. Cannabis is almost always smoked, often mixed with tobacco. Almost all consumption of herbal cannabis and resin is of illicit material. Some therapeutic benefit as an analgesic has been claimed for cannabis, and dronabinol is a licensed medicine in some countries for the treatment of nausea in cancer chemotherapy. Cannabis products and Δ9-THC are under international control.

For more information on this substance see the EMCDDA webpage on cannabis
And see synthetic cannabinoids and 'Spice'