Agarwood essential oil is derived from the heartwood of the Aquilaria tree, a species native to Southeast Asia. The tree produces agarwood as a response to fungal infection, leading to the formation of a dense, aromatic resin. This resin is then harvested and distilled to produce agarwood essential oil, also known as oud oil. Agarwood oil has a long history in traditional medicine, particularly in Ayurvedic and Chinese practices, where it has been used for its anti-inflammatory, analgesic, and calming effects.