Put simply, hemp, marijuana, weed, and cannabis are part of the same species of plant. It’s the level of THC in the plant that determines its appropriate name. For instance, hemp is a legal term to describe cannabis plants that contain less than 0.3% THC. Weed is just a slang word for cannabis, and marijuana refers to cannabis plants with more than 0.3% THC. In this article, we will break down the naming conventions further and will delve into their historical references.