Herbal is "a collection of descriptions of plants put together for medicinal purposes."

Expressed more elaborately, it is a book containing the names and descriptions of plants, usually with information on their virtues (properties) – and in particular their medicinal, tonic, culinary, toxic, hallucinatory, aromatic, or magical powers, and the legends associated with them.

A herbal may also classify the plants it describes, may give recipes for herbal extracts, tinctures, or potions, and sometimes include mineral and animal medicaments in addition to those obtained from plants.

Herbals were often illustrated to assist plant identification.