Herbalism also known as Herbal medicine and phytotherapy, is a folk and traditional medicinal practice based on the use of plants and plant extracts.
Finding healing powers in plants is an ancient idea. People in all continents have long used hundreds, if not thousands, of indigenous plants for treatment of various ailments dating back to prehistory. There is evidence that suggests Neanderthals living 60,000 years ago in present-day Iraq used plants for medicinal purposes (found at a burial site at Shanidar Cave, Iraq, in which a Neanderthal man was uncovered in 1960. He had been buried with eight species of plants).  These plants are still widely used in ethnomedicine around the world.
The first generally accepted use of plants as healing agents were depicted in the cave paintings discovered in the Lascaux caves in France, which have been Radiocarbon dated to between 13,000 - 25,000 BCE.
Anthropologists theorize that over time, and with trial and error, a small base of knowledge would have been acquired within early tribal communities. As this knowledge base expanded over the generations, the specialized role of the shaman emerged. The process would likely have occurred in varying manners within a wide diversity of cultures.
Plants have an almost limitless ability to synthesize aromatic substances, most of which are phenols or their oxygen-substituted derivatives such as tannins. Most are secondary metabolites, of which at least 12,000 have been isolated, a number estimated to be less than 10% of the total. In many cases, these substances (esp. alkaloids) serve as plant defense mechanisms against predation by microorganisms, insects, and herbivores. Many of the herbs and spices used by humans to season food yield useful medicinal compounds.
The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Pharmacologists, microbiologists, botanists, and natural-products chemists are combing the Earth for phytochemicals and leads that could be developed for treatment of various diseases. In fact, many modern drugs have been derived from plants.
The use of herbs to treat disease is almost universal among non-industrialized societies. A number of traditions came to dominate the practice of herbal medicine in the Western world at the end of the twentieth century:
* The Western, based on Greek and Roman sources,
* The Ayurvedic from India, and
* Chinese herbal medicine (Chinese herbology).
Many of the pharmaceuticals currently available to Western physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine.