Marijuana refers to the dried-out leaves, flowers, stems, and seeds of the hemp plant, Marijuana Sativa. The plant is a common weed that grows freely in most areas of the world. Marijuana, also known as cannabis, is also probably the most commonly used abusable substance in the world, with estimates in the hundreds of millions of daily users. It is most frequently smoked in smalL hand-rolled cigarettes called "joints." Alternatively, users employ regular pipes, or water pipes called "bongs." The resin from the flowering tips, or hashish, is more potent and may also be smoked.