Cannabis sativa L. (marijuana; Cannabaceae) is a plant with worldwide distribution, yielding fiber and food, as well as a psychoactive drug. Cannabinoids and in particular the main psychoactive Δ 9 -THC are promising substances for the development of new drugs and are of high therapeutic potential. This review gives an overview of Cannabis classification, the current verities, botanical features, genomics, chemicals constituents, cellular site and biosynthesis of cannabinoids. Furthermore, the different cultivation and breeding forms, changes in cannabinoids over time, method of harvesting, drying and processing of Cannabis are extensively described in addition to the analytical procedures for standardization of Cannabis based medicinal extracts. Finally, some aspects of current approved Cannabis based medicine and its ways of administration are described.