Crude drugs are naturally occurring substances derived from plants, animals, bacteria or fungi that are used for medicinal purposes. They include whole or cut plants, plant or animal parts, juices, glands, dried plant secretions and animal extracts. Crude drugs can be classified in several ways including by their source (plants, animals, minerals), plant organ (roots, leaves, fruits), pharmacological effects, chemical constituents or taxonomic classification. The most common sources are higher plants, microbes, animals and marine organisms. Crude drugs are either organized tissues like herbs, fruits, barks or unorganized substances like juices, oils, gums or resins.