What are essential oils

Essential oils are volatile substances produced within the aromatic plants and isolated by a process such as distillation or extraction. They are in liquid form but evaporate easily into the atmosphere, releasing the characteristic aroma and the particular properties of the plant from which they originated. 

Used since antiquity in therapeutic pharmacology, perfumery, cleaning and perfuming the premises. Now widely used because of the effect they have on the mental health of humans via inhalation. 
Their use has beneficial effects in humans but must be used with caution.
Click HERE to see their properties and HERE to see how to use them.