The cannabis plant, which has the Latin name Cannabis Sativa L. has a couple of different subtypes. One of these subtypes is the marijuana plant, which is often referred to as simply cannabis. This cannabis subtype contains the intoxicating compound THC or tetrahydrocannabinol (tET-tra-High-dro-Cani-buh-nahl). THC is the compound which is responsible for the "high" that people get when they ingest marijuana.
Another subtype of Cannabis sativa L. is the hemp plant. Hemp has been used for many thousands of years and was one of the very earliest plants ever grown for its use as a textile fiber. In the 1600's, colonists in Virginia were cultivating the hemp plant which they used to make rope, sails for their ships and even their clothing. The hemp plant, unlike cannabis, has been bred over centuries for its fiber content and contains a negligible amount of THC, so little in fact, that you do not get any intoxicating effect from ingesting it. The two plan subtypes, both marijuana and hemp, contain a class of chemical compounds called cannabinoids (Can-nah-buh-noids) and there are more than a hundred of these compounds in Cannabis Sativa L. Because of its intoxicating qualities, THC is the best known of the cannabinoids and besides its ability to induce a high, it has some well-publicized therapeutic effects. Another of the cannabinoids is CBD (or cannabidiol) and it also has therapeutic effects, but without the potential of an intoxicating high. Both THC and CBD are classified as cannabinoids.