An herb is a flowering plant that is valued for its medicinal properties, flavor, or scent.  A broader definition also includes fungi, fruits, roots, vegetables, and all plants.  Occasionally, enzymes, minerals, or hormones can be included as "herbal medicines."

Herbal Supplements are defined by the Dietary Supplement Health and Education Act (DSHEA) as products that are intended to supplement the diet and that contain herbs or other botanical substances, amino acids, vitamins, minerals, or a combination of these.  If a products meets this definition, it may be sold in stores, and its supplier can claim health values as long as there is some scientific evidence.