Pot

Pot is a slang term for cannabis, also called marijuana, weed, dope, grass, and hash, among other names. Pot contains Tetrahydrocannabinol (THC) and Cannabidiol (CBD); the former is what causes an altered mental state–called a “high”–in users, whereas the latter is non-psychoactive. Pot can be ingested by inhaling from a pipe, bong, vaporizer, or other similar tool, or can be consumed by eating products that contain THC or CBD. 

According to the Center for Disease Control and Prevention (CDC), pot is the most widely used drug in the United States.  The legality of pot products containing THC varies from state to state, which can be seen on this map. Products containing only CBD, however, are mostly legal throughout all 50 states. Both THC and CBD remain illegal under federal law, however.

Pot–especially CBD–is becoming an increasingly popular tool for medical treatments. According to this article from Harvard Health Publishing, CBD may be useful in treating chronic pain, anxiety, and sleep disorders, though further research is required to prove its efficacy. For a further discussion of the medical uses of pot, see this article from the National Institute on Drug Abuse.