Entourage effect is a well established and important mechanism when as much of the native plant is present when consumed. It refers to the fact that when multiple phytocannabinoids (CBD, THC, CBC, etc) bind to the receptors it will produce a larger effect then if the isolated parts are present alone. This is why CBD is usually combined with terpenes or other phytocannabinoids when put into products. This paper does a very good job of explaining this in much more detail and if you want higher level knowledge, please read this paper: Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects
Terpenes have gained a lot of attention and research lately. There are about 11 common terpenes found in most strains. The Terpenes listed in the picture are the most common terpenes found in any strain. Terpenes are produced by plants for a couple of reasons. They produce them to either attract potential pollinators or sometimes to ward off animals from eating them. In humans we respond to the various smells and tastes of the terpenes. Think of the uplifting effects of a zest of a lemon or the calming effects of lavender. A lot of the variant effects of each strain is due to the blends of terpenes, along with the varying ratios of cannabinoids, They produce their own effects on the body and are used in products from; essential oils, soaps and beauty products. Our body has receptors that Interact with these terpenes on their own. Yet, when they are combined with cannabinoids it will produce a more profound effect.