"Cannabinoids are chemical compounds that act on receptors in the endocannabinoid system. There are currently 85 known cannabinoids, all unique molecules that cause a variety of effects on the endocannabinoid system.
Endocannabinoids are the cannabinoids produced naturally in our bodies. One of the more famous endocannabinoids is anandamide, derived from the Sanskrit word for bliss.
Phytocannabinoids are the cannabinoids produced by the cannabis plant (and other plants like echinacea). Phytocannabinoids are concentrated in the resin found in the trichomes (small hairs on the cannabis flower). The two most popular phytocannabinoids are THC and CBD. Here is a list of some of the known phytocannabinoids:
- THC (tetrahydrocannabinol): produces psychoactive effects by binding to CB1 receptors in the brain. Binds to both CB1 and CB2 receptors. Mimics the endocannabinoid anandamide.
- CBD (cannabidiol): non-psychoactive. CBD has little affinity for CB1 and CB2 receptors, but favors CB2 receptors. CBD has been shown to suppress the effects of THC by blocking uptake of THC at cannabinoid receptors
- CBG (cannabigerol): non-psychoactive, CB1 receptor antagonist
- CBC (cannabichromene): non-psychoactive, does not effect receptors
- CBN (cannabinol): product of THC degradation, weak psychoactive effect, content increases when the plant is exposed to light and air
- THCV (tetrahydrocannabivarin): Reduces psychoactive effects of THC by binding to CB1 receptors. Noted in certain strains of cannabis from central Asia and southern Africa
- CBL (cannabicyclol)
- CBDV (cannabidivarin)
- CBCV (cannabichromevarin)
- CBGV (cannabigerovarin)
- CBGM (cannabigerol monomethyl ether)
While THC is the most common cannabinoid in the current market, demand has increased for cannabis containing higher amounts of CBD, THCV and other cannabinoids."
 - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2241751/
 - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866040/
 - http://www.ncbi.nlm.nih.gov/pubmed/17712814