The Endocannabinoid system is one of, if not, the most important physiological systems involved in establishing and maintaining human health. The Endocannabinoid System regulates all our body systems and brings about Homeostasis.  Homeostasis is the body's way of maintaining internal stability, health and function.  
Homeostasis is a balanced state of being.

The ECS is responsible for such things as memory, motivation, higher information processing, pain perception, appetite, fertility, immune system and even controls the spread of cancerous cells.

Endocannabinoids are made from essential fatty acids from your diet and are produced on demand from the nerve cell or immune cell.. They act locally to produce homeostasis and are immediately broken down by special enzymes.

Everyone has a unique endocannabinoid system. Even identical twins have different systems. 

Cannabinoid receptors are found throughout the body embedded in cell membranes and are believed to be more numerous than any other receptor system. There are two known, and three suspected types of cannabinoid receptors present in the human body. The two that are confirmed are CB1, expressed mainly in the brain (central nervous system or "CNS"), but also in the lungs, liver and kidneys, and CB2 expressed mainly in the immune system and in hematopoietic cells

Cannabinoid receptors are activated by the body's own endogenous cannabinoids. The two main endocannabinoids are 
Anandamide and 2 Arachidonoyl glycerol (2AG).
Phytocannabinoids such as  Delta-9 Tetrahydrocannabinol (THC), cannabidiol (CBD)  and cannabinol (CBN) found in both Marijuana and hemp also activate the cannabinoid receptors. After the receptor is engaged, multiple intracellular signal transduction pathways are activated.