A strain refers to the named variations of cannabis that differ in appearance, aroma, and effect. Cannabis grows natively in different regions of the world and has been selectively bred for various characteristics. Terms like “sativa” and “indica” describe different structural differences in the plant: narrow vs. broad leaves, tall vs. short stature, etc. Cannabis strains that has been crossbred are called hybrids, which make up a vast majority of cannabis available today.