As far back as 5000 BCE, Sumerians used herbs in medicine. Ancient Egyptians used fennel, coriander and thyme around 1555 BCE. In ancient Greece, in 162 CE, a physician by the name of Galen was known for concocting complicated herbal remedies that contained up to 100 ingredients. 

In general use, herbs are any plants used for food, flavoring, medicine, or fragrances for their savory or aromatic properties. Culinary use typically distinguishes herbs from spices. Herbs refer to the leafy green or flowering parts of a plant (either fresh or dried), while spices are produced from other parts of the plant (usually dried), including seeds, berries, bark, roots and fruits.

In botanical English, the word "herb" is also used as a synonym of "herbaceous plant".

Herbs have a variety of uses including culinary, medicinal, and in some cases, spiritual. General usage of the term "herb" differs between culinary herbs and medicinal herbs. In medicinal or spiritual use any of the parts of the plant might be considered "herbs", including leaves, roots, flowers, seeds, root bark, inner bark (and cambium), resin and pericarp.