Oud is one of the most expensive and desirable perfume ingredients in the world. It has an intoxicating musky scent and is derived from the tropical Agarwood tree found naturally growing in the Middle East. Oud is a key ingredient in old and new Arabic perfumery, renowned as an element within high-quality incense. Historians can trade the use of Oud to the times and incontrovertible evidence lies within the scriptures of various ancient cultures. Oud is valued strongly by perfumers for its warm sweetness mixed with woody and balsamic notes. An aromatic and complex scent. When used in perfume Oud is most often a base note, which tends to remain on the skin long after the other notes dissipate. Base notes are very rich, heavy and long-lasting.