Agarwood, also known as oud, oodh or agar, is a dark resinous heartwood that forms in Aquilaria and Gyrinops[1] trees (large evergreens native to southeast Asia) when they become infected with a type of mould. Prior to infection, the heartwood is relatively light and pale coloured; however, as the infection progresses, the tree produces a dark aromatic resin in response to the attack, which results in a very dense, dark, resin embedded heartwood. The resin embedded wood is commonly called gaharu, jinko, aloeswood, agarwood, oroud (not to be confused with 'Bakhoor') and is valued in many cultures for its distinctive fragrance, and thus is used for incense andperfumes.

One of the main reasons for the relative rarity and high cost of agarwood is the depletion of the wild resource.[2] Since ***5 Aquilaria malaccensis, the primary source, has been listed in Appendix II (potentially threatened species) by the Convention on International Trade in Endangered Species of Wild Fauna and Flora.[3] In ***4 all Aquilaria species were listed in Appendix II; however, a number of countries have outstanding reservations regarding that listing.[3]