The essential oils are aromatic essences extracted from plants, flowers, trees, fruits, bark, grasses and seeds with distinctive therapeutic, psychological, and physiological properties, which improve and prevent illness. There are about 150 essential oils. Most of these oils have antiseptic properties; some are antiviral, anti-inflammatory, pain-relieving, antidepressant and expectorant. Other properties of the essential oils which are taken advantage of in aromatherapy are their stimulation, relaxation, digestion improvement, and diuretic properties. To get the maximum benefit from essential oils, it should be made from natural, pure raw materials. Synthetically made oils do not work.

Aromatherapy is one of the fastest growing fields in alternative medicine. It is widely used at home, clinics and hospitals for a variety of applications such as pain relief for women in labor pain, relieving pain caused by the side effects of the chemotherapy undergone by the cancer patients, and rehabilitation of cardiac patients.

Aromatherapy is already slowly getting into the mainstream. In Japan, engineers are incorporating aroma systems into new buildings. In one such application, the scent of lavender and rosemary is pumped into the customer area to calm down the waiting customers, while the perfumes from lemon and eucalyptus are used in the bank teller counters to keep the staff alert.