The endocannabinoid system (ECS) refers to a cell-signalling network present throughout the bodies of humans and most other vertebrates. It is generally described as comprising three core components: cannabinoid receptors located on cell surfaces, endogenous signalling molecules known as endocannabinoids, and the enzymes that synthesise and degrade those molecules.
In academic literature the ECS is characterised as a homeostatic system, meaning it is associated with keeping internal biological conditions within a stable range. Researchers describe it as being involved in modulating processes such as appetite regulation, sleep cycles, immune signalling, mood and the perception of pain.
The ECS is the principal biological pathway through which plant-derived cannabinoids are understood to exert their effects. Because of this, it is a major focus of ongoing scientific investigation rather than a settled area of clinical practice.