What are essential oils?

An essential oil is a natural liquid product containing volatile (easily evaporated at normal temperatures) chemical compounds, extracted from a single plant species. Not all plants produce essential oils, and in the plants that do, the essential oil may be found in the roots, stems, leaves, flowers, or fruits.
An essential oil is essential in the sense that it contains the essence of the plant’s fragranceā€”the characteristic fragrance of the plant from which it is derived.