An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. An oil is “essential” in the sense that it contains the “essence of” the plant’s fragrance - the characteristic fragrance of the plant from which it is derived. Essential oils are generally extracted by distillation, often by using steam. Other processes include expression, solvent extraction, absolute oil extraction, resin tapping, and cold pressing. They are used in perfumes, cosmetics, soaps and other products, for flavoring food and drink, and for adding scents to incense and household cleaning products.