From the point of view of science essential oils - a multicomponent organic compounds terpenes, alcohols, aldehydes, ketones and hydrocarbons produced by aromatic plants.
Currently, there are about 200 different essential oils, with proper application, to a pronounced therapeutic effect and have no side effects.
Essential oils give each plant its individual, unique flavor.
Essential oils are different volatility - that is quickly evaporate at room temperature or above. This is one explanation of why the summer, we feel much more flavors than at any other time of year, and we feel a lot better than in winter.
In essence, there is another feature: it is, despite its name, is not fat.