Essential oils are called "essential" because they easily dissolve in alcohol to form essences. (Essences are extracts that have the fundamental properties of a substance in concentrated form.) Essential oils are used in flavorings, perfumes, disinfectants, medicines, and other products. One of the main ingredients of these oils is a substance belonging to the terpene group (terpene is a type of hydrocarbon). Essential oils are naturally occurring, volatile (readily convert to a gas), scented oils found in the leaves, pods, and other parts of plants.
Examples of essential oils include bergamot, eucalyptus, ginger, pine, spearmint, and wintergreen oils.