According to Wikipedia, an essential oil is a “concentrated hydrophobic liquid containing volatile aroma compounds from plants” or more simply put “the oil of the plant from which they were extracted”. With companies like DoTerra and Young Living claiming over a billion dollars in sales per year, essential oils have made their way into thousands of homes.
Essential oils have been used for centuries: ancient Egyptians used perfumed oils and medieval healers even treated patients with plant extracts. Currently, popular uses include cooking, aromatherapy, treating minor ailments like cuts and scrapes, DIY natural cleaning supplies, meditation aids, immune support, illness prevention, etc.