The bark of cinnamon, a commercially important spice.

The terms herb and spice are popular terms for plants or plant products that are used as flavorings or scents (e.g., spices and culinary herbs), drugs (e.g., medicinal herbs), and less frequently as perfumes, dyes, and stimulants.

Many herbs and spices are edible but may be distinguished from fruits and vegetables by their lack of food value, as measured in calories. Unlike fruits and vegetables, their usefulness has less to do with their primary metabolites (e.g., sugars and proteins) than with their secondary metabolites (compounds commonly produced to discourage pathogens and predators). The distinct flavors and smells of spices and culinary herbs are usually due to essential oils, while the active components of medicinal herbs also include many kinds of steroids, alkaloids, and glycosides. Most plants referred to as herbs or spices contain...