In culinary usage spices are usually roots, seeds, berries, bark, and other fruits (see Spices), while herbs are leaves or flowers. The aromatic vegetables, such as garlic and shallots, comprise a third group of flavorings.
An experienced saucier uses herbs at several stages of the sauce-making process. The decision as to when to use a certain herb depends on the herb’s flavor and its reaction to heat. Some herbs contribute to the background flavor of a sauce, while others are added at the last minute to add finesse and freshness or a character of their own.