CBD is short for cannabidiol, which is the dominant cannabinoid found in the hemp plant. As a cannabinoid, CBD is able to bind to cannabinoid receptors located throughout the body, enabling a process in which the body may achieve homeostasis as part of the endocannabinoid system that’s present in all mammals.
CBD was discovered in 1940, making it one of the first cannabinoids to be studied by researchers. CBD does exist in the marijuana plant as well, but it’s derived from hemp both for reasons relating to legality, and because it’s easy to isolate, as it can make up anywhere from 10 to 20% of the plant material.