Also called as the king of essential oils, the Frankincense essential oil can be found in many products used on skin and hair. By cutting through the bark of the Boswelia tree, oil can be extracted from the sap. When the resin hardens, it is scraped off the tree. Although it can be used dry, it is steamed to produce essential oil. Using its relaxing woody aroma as an essential oil in a diffuser can aid in promoting relaxation. It can also aid peace, harmony, and meditation. It has a woody, spicy smell and can either be inhaled or absorbed through the skin. Ayurvedic medicine uses frankincense oil to treat arthritis, digestion and asthma in addition to improved oral health.