Aromatherapy
Aromatherapy is a form of therapy that uses volatile liquid plant materials, known as essential oils (EOs), and other aromatic compounds from plants for the purpose of affecting a person's mood or health. Essential oils, phytoncides and other natural VOCs work in different ways. At the scent level they activate the limbic system and emotional centers of the brain. When applied to the skin (commonly in form of "massage oils" i.e. 1-10% solutions of EO in carrier oil) they activate thermal receptors, and kill microbes and fungi.
http://en.wikipedia.org/wiki/Aromatherapy