For starters, TAC is short for Total Active Cannabinoids which is the number of detectable cannabinoids present in a cannabis product. These available cannabinoids work together in synergy by what is known as the entourage effect to give rise to the overall effects of the natural herb. THC is the psychoactive cannabinoid in the cannabis plant matrix that gives rise to the euphoric feeling users experience during recreational use. However, there is more to the cannabis plant than just the THC content of the strain and many cannabis users are starting to come to this reality.