Essential oils are volatile substances from plants or drugs. When the plant is rubbed they are released to reach the olfactory mucosa of the upper wall of the nose and the olfactory nerve irritation. The result is the characteristic scent of a plant or drug that is firmly impressed in our mind and that we connect with the plant. An essential oil is a complex mixture of fragrances. What usually dominates the aroma are the main components of the essential oil such as peppermint oil in the menthol or thymol in thyme oil. The term "oil" comes from the fact that essential oils such as the fatty oils are only soluble in lipophilic solvents, whereas they are not or only to a very limited degree in water. These two oil types do not have anything else in common. The plant stores from this essential oil in very special, microscopically recognisable cellular structures. Such cells are known as oil cells, oil containers, oil ducts and gland shelters. You collect essential oils either by steam distillation or cold pressing (only citrus oils).