Oud is a fragrant oil extracted from the resin of the heartwood of the aquilaria tree, which is primarily found in Southeast Asia. It is one of the most expensive raw materials in the world, and it takes a long time to develop naturally. Oud has a distinct woody aroma, making it a popular ingredient in many woodsy fragrances that feature notes like sandalwood. It is warm, musky, animalic, and slightly sweet, with a deeply rich and complex fragrance that lingers long after its been applied or burned. Oud is often used as a base note in perfumery, providing a signature depth and richness to the scent. Due to its rarity and the difficulty of obtaining it, oud is considered a luxury ingredient in perfumery.