Every human being (and other mammals) have an Endocannabinoid System. This system is in place to regulate one of the most fundamental concepts in biology: Homeostasis.

Homeostasis is defined by Cambridge Dictionary as "the process by which a living thing or a cell keeps the conditions inside it the same despite any changes in the conditions around it". This balance is essential for the health of all other systems in our bodies. Our systems are always striving for balance, keeping neuro transmissions, blood sugars, body temperature, etc. from going to far in one direction or the other. When our Endocannabinoid System is deficient, other systems fall out of balance. The absolute beauty of CBD (as well as all other plant cannabinoids) is that the cannabinoid receptors in our bodies accept them as if they were a key to unlock the potential of this amazing system.

Read more here in a wonderful article from Leafly:

https://www.leafly.com/news/science-tech/what-is-the-endocannabinoid-system