Herbalism, also known as phytotherapy, is folk and traditional medicinal practice based on the use of plants and plant extracts.

The use of herbs to treat disease is almost universal among non-industrialized societies. A number of traditions came to dominate the practise 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.