Essential oils, or aromatherapy oils, are the fragrant essence of fruit, seeds, flowers, roots, leaves, barks, or wood. These highly concentrated liquid oils are the foundation of aromatherapy, which is based on the idea that the aromatic oil from a plant has healing properties.
To capture the oils, manufacturers usually heat the plant part in water and collect the steam. As the steam condenses, the essential oil is distilled from the water.
The inhaled aroma from these "essential" oils is widely believed to stimulate brain function.