Aromatherapy is a unique branch of herbal medicine that utilises the medicinal properties found in the essential oils of various plants to treat conditions ranging from infections and skin disorders to immune deficiencies and stress.  Essential oils have been used therapeutically from ancient times in countries such as Egypt, India, China and Italy. In Europe, essential oils were first used in ritualistic practices during the Middle Ages as a means of combating illness.  Aromatic plants and essential oils were supposed to control the impurity of the air. It was common practice to inhale from sponges soaked in vinegar or a lemon stuck with cloves to ward of disease, and candles scented with rose petals, cloves and musk were burnt in sick rooms as a preventative measure. In most of the world, plant essences are used today as therapeutic agents in everything from antiseptic creams and skin ointments to liniments for arthritis.
The essences are extracted from flowers, fruit, leaves, branches, roots and resins.  The small molecular size of the oils aid in their easy absorption into the body tissues, contributing greatly to their therapeutic value. 
The aromatic molecules travel to the limbic system in the brain where they create impressions associated with previous experiences and emotions. Because the limbic system is directly connected to those parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels and hormone balance, scientists have learned that the inhalation of oil fragrances may be one of the fastest ways to achieve physiological or psychological effects. Aromatherapist, Anne Verily of California, explains “As these vapours pass through the olfactory nerves, they effect the following areas of the brain: the cortex, which governs all the intellectual processes; the pituitary, which oversees all hormonal activity, including adrenal hormones; and the hypothalamus, which plays a direct role in controlling anger and aggression.
Aromatherapy is very effective for bacterial infections of the respiratory system, immune deficiencies and numerous skin disorders.  The antimicrobial effects of the essential oils are due to their ability to enter the cell walls of microbes and cut of oxygen. This stops the formation of energy within the cells of microbes and kills them. The immediate and often profound effect that the essential oils have on the central nervous system also makes aromatherapy an excellent method for stress management.
Oils are readily absorbed through the skin. The general applications are baths, massages, hot and cold compresses, spritzers or simple topical application of the diluted oils.
Selecting essential oils from the different outlets can be very confusing. Pure essential oils are expensive due to the processes involved in extracting these precious oils from the plant source.  While these essential oils may seem expensive, one or two drops will go far, making them quite cost effective. In contrast, the effectiveness of lower grade oils, or oils that have been diluted, is poor. The best way to purchase essential oils is from a supplier who specialises in the use of essential aromatherapy oils.
There are many different wonderful uses for essential oils, but one must practice absolute caution when using them. Always consult with a qualified Aromatherapist before use.