If you have ever experienced the scent of a rosemary bush, you’ve experienced the aromatic qualities of an essential oil. Having been around for thousands of years, various cultures have used them for medicinal and health purposes. You will find them used in aromatherapy, household cleaning agents and beauty care products as well as natural medicine treatments.
Essential oils are simply a concentrated form of the oils found naturally in the flowers, leaves, bark, stems, seeds and other parts of plants. When the oils are extracted, they maintain the characteristic fragrance, or essence, of that plant.
The method of extraction varies from oil to oil, depending on the part of the plant that was used to obtain the oil. Most are steam distilled and some like citrus oils, are cold pressed. The essential oil is literally the life force of the plant. Oils serve as the defense system in plants. They oxygenate the plant and carry nutrients, vital elements and chemical constituents to every cell in the plant. They contain the healing nutrients including trace minerals, vitamins, hormones, amino acid precursors and other components. They give the plant the ability to destroy infections, stave off infestations, initiate and maintain growth and repair structural damage.
In addition, essential oils have the capacity to change the electrical frequency of the body. When frequencies drop, disease sets in. Essential oils have the highest frequency of any substance known. As living substances, their frequency is harmonic with the human frequency. When we come in contact with them, our body frequency is raised to a degree that we become inhospitable to pathogenic organisms. 
There two major ways essential oils can be used: 1. inhaled often through a diffuser that distributes the plant’s essence into the air, entering the body through the respiratory system. 2. Absorbed through the skin.
When oils are diffused through the air they can kill most air-borne microorganisms. Choose oils that benefit respiratory problems. Inhalation allows the oils to come into direct contact with the mucus membrane lining. There are 800 million nerve endings in the nose that detect odors. The olfactory system in the nasal cavity activates the limbic system of the brain that then activates the endocrine system to stimulate moods as well. Aroma therapy can have mild or profound psychological effects from uplifting the spirit, to promoting mental alertness. Studies have shown that lavender oil reduces stress and improves patients with heart disease and that peppermint relieves nausea, vomiting and headaches. 
When applied to human skin, essential oils carry the same healing force as they do to the plant. They are highly concentrated, at least 50 time more therapeutically potent than the plant itself or herbs made from the plant and need to dispersed in carrier oils (like almond, jojoba, olive or coconut). Essential oils detoxify the body. Oxygen pushes unwanted chemicals out of the cell. Normal cell function and balance is established only with sufficient oxygen. They are soluble with the lipids in the cell membranes and penetrate into the cells. When applied to the skin, within 21 minutes, essential oils will penetrate every cell within the body. 
The benefits of essential oils come from their antioxidant, antimicrobial and anti-inflammatory properties.  Be sure to use pure essential oils that are 100% pure oil extracted directly from the botanical plant source without any synthetics or impurities. The internal use of essential oils should only be administered under the supervision of a healthcare practitioner. Based on the composition of an oil, there may be areas of the body where it can be applied and others that should be avoided. Check the product label.
 Goldberg, Jane G., PhD, “What are Essential Oils”
Billie Nicholson, Editor