The cannabinoids found in hemp and cannabis can be thought of as the plant’s primary active ingredients. Also called phytocannabinoids (or pCB’s), they’re used by the plant to protect itself against UV light, insects, cold habitats, etc. These cannabinoids are produced in different metabolic stages; typically, precursors like olivetolic acid are used to create a first cannabinoid called CBG.
Olivetolic acid —> CBGa —> CBDa —> CBD
CBG, which is known as the “mother cannabinoid”, is then converted mostly into CBD (in the case of hemp), or into THC (in the case of ‘marijuana’). Cannabinoid levels within the plant continue to diversify and swell until the plant is fully mature. At that point, it may contain up to 120 cannabinoids! These include:
...and many more. Also keep in mind that an unprocessed cannabis or hemp plant will contain acid forms of these cannabinoids — CBDa, THCa, CBCa, CBGa, etc — that still have their carboxyl group still attached. In order to make CBD oil, cannabinoids are gently heated and lose this carboxyl group. With a slightly smaller molecular weight, these ‘decarbed’ cannabinoids are much more bioavailable within the body and brain.
Plant cannabinoids were only discovered recently, in the scheme of things. CBN (cannabinol) was discovered first, in 1940. CBD was discovered shortly later, in 1942.
For many years, researchers knew about cannabinoids and their biochemical actions, but didn’t understand why such compounds could work so powerfully. That all changed in the early ‘90s, once internally produced cannabinoids were discovered.