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Cannabinoids are a class of diverse chemical compounds that activate cannabinoid receptors. These include the endocannabinoids (produced naturally in the body by humans and animals), the phytocannabinoids (found in cannabis and some other plants), and synthetic cannabinoids (produced chemically by humans). The most notable cannabinoid is the phytocannabinoid ∆9-tetrahydrocannabinol (THC), the primary psychoactive compound of cannabis. However, there are known to exist numerous other cannabinoids with varied effects.