The law as it pertains to the use and sale of cannabis (a.k.a. marijuana) differs from country to country, and from state to state in the USA. In some regions, groups of people may qualify for its use as a medicine. Cannabis can be used as a treatment for symptoms for a variety of medical conditions.
Cannabis use has become way more acceptable in the eyes of the world. Some countries, and a large number of states in the US, have legalized cannabis for medical or recreational use. While some cannabis advocates can be a little unrealistic when they describe the benefits of cannabis use, there is a lot of evidence that it has genuine medical applications.