Essential oil is responsible for the aromatic expression of a plant. Approximately 10% of the world's plants contain essential oil, each of them metabolizing the elements of its environment in a different way resulting in a specific scent. These oils act as part of the immune system of the plant by helping it to survive among parasitic insect and microbe communities and to cope with environmental changes. Essential oils also play an important role in attracting pollinating insects and other mutually symbiotic organisms, including humans who have learned to cultivate these plants and extract their oils for a variety of uses.

Throughout history, people have looked to plants for natural healing due to their therapeutic properties. Essential oils are antibacterial, antiviral, anti-inflammatory, skin rejuvenating, blood revitalizing, and soft-tissue healing. Oils can be helpful for hormone balancing, fertility, and mood stabilization. They are also used to soothe, relax, energize, uplift, focus, and restore energy. Essential oils help enhance sensory experience and to deepen meditation.