The endocannabinoid system is a complex network of lipid-based endocannabinoids (cannabinoids which are produced naturally in the body), cannabinoid receptor proteins. The system is distributed throughout the body, including in the central nervous system and the peripheral nervous system. The reactions that take place in this system are extremely important for many bodily functions, including brain functions.

Interactions between endocannabinoids, cannabinoids, and receptors play an important role in physiological and cognitive processes including fertility, pregnancy, during prenatal and postnatal development. They also influence mood, emotions, appetite, pain-sensation and memory. Cannabinoids found in the cannabis plant (the most well-known being CBD and THC) interact with this system in similar ways to the endocannabinoids.