Cannabis
Cannabis names any of a number of families of bushy cane plants (including cannabis sativa, cannabis indica, and cannabis ruderalis.) Different members of these families have adapted or been bred for various purposes. Despite the variety of uses these plants posess, policy has kept cultivation of any cannbis plant illegal in many countries around the globe.

Hemp
Cannabis bred for industrial use is often referred to as industrial hemp. Hemp appears to be a very promising natural resource; it's hurd can be made into paper and it's fibre can be made into building materials. It can also be used as cheap and plentiful raw material for producing biomass (alcohol fuel) and plastic. Widespread use of such a resource could have a greatly beneficial environmental impact.

Hempseed
The seed of the cannabis plant is often referred to as hempseed. Hempseed has been used as a staple ingredient in many recipes throughout the centuries, and it appears to be a very promising nutritional resource, composed of an optimal ratio of essential fatty acids (EFA's) for human physiology. In short, hempseed is edible, 100% good for you, and contains no THC. Hempseed oil also has many possible industrial uses, including the manufacturing of paint and varnish products.

Marijuana
Cannabis bred for herbal and medicinal use is often referred to as medicinal marijuana. Marijuana appears to be very promising at treating diseases such as glaucoma and relieving the pain of AIDS patients. However, there are many myths surrounding the topic of marijuana health.

Pot
Cannabis bred purely for recreational use is often referred to as pot - because that's what it's usually grown in. To many, this practice is no less socially acceptable than, say, distilling one's own wine. This is the touchiest issue surrounding the cannabis plant. If scientifically proven to be overall no more harmful to a human life than alcohol, continued criminalization of cannabis users is totally unjustifiable.