Breaking it down into basics, essential oils (sometimes referred to as EOs) are volatile aromatic compounds extracted from the bark, flowers, leaves, roots, seeds, stems, and other parts of plants. They give a plant its distinct aroma and play a crucial role in the survival of the plant as a whole, as well as its participation in the chain of life. Using the word “volatile” in reference to essential oils indicates the incredible ability of their tiny organic molecules to change state from liquid to gas very quickly when at room temperature. Each essential oil has a unique composition based on the variety of its chemical constituents that vary from plant to plant and even species to species. Each essential oil consists of both primary and trace constituents. Scientists are always learning about and discovering new constituents and the synergistic play they have in each essential oil as well as how they react when combined into blends.