Delta 9 THC is the primary psychoactive compound in cannabis plants. Its role in the plant is to protect it from the sun’s harsh rays as well as insect invasion. Modern cannabis plants contain high levels of THC purely because of human intervention.
Raphael Mechoulam first studied THC in 1964. He was the first scientist to extract THC from cannabis and discovered that the molecule could cross the blood-brain barrier. He was also the first to realize that THC was responsible for the psychoactive effects of smoking marijuana, opening the door for further study of the body’s interaction with cannabinoids.
People usually refer to delta 9 THC as just THC, dropping the delta 9 specifier. Chemically, delta 9 THC gets its name from the location of a carbon double-bond. Isomers of delta 9 THC, like delta 8 and delta 10 THC, have this double bond in a different locations (the eighth and tenth positions, respectively).