Fragrances are substances that give off a pleasant smell. They can be found in many forms, such as PERFUMES, ODORS, SCENTS, AROMAS, and ESSENCES. PERFUMES are the most concentrated form of fragrance, and are usually made from essential oils and other aromatic compounds. ODORS are less concentrated than PERFUMES, and are often associated with unpleasant smells. SCENTS and AROMAS are similar to ODORS, but are usually more pleasant. ESSENCES are the most subtle form of fragrance, and are often used in aromatherapy.