The use of plant extracts for health, cosmetic, and dietary purposes has a rich history that has evolved parallel to the development of human civilization. Technology has unleashed sophisticated means for distilling plant materials and isolating their essential oils—substances that have incredible applications to human health and wellness. Essential oil use and the science behind it is an exciting field that is progressing at a rapid pace. As science continues to expand, we are no longer limited by tradition. A wide variety of essential oil applications have been studied to confirm their safety and effectiveness. Until now, the scientific knowledge surrounding essential oils has not existed in a single, authoritative source. We will give you the tools to think about the real-world applications of essential oils by embracing the traditions of the past while simultaneously using emerging science to create a new paradigm of essential oil use.