Agarwood, Aloeswood or Gharuwood is a fragrant dark resinous wood used in incense, perfume, and small carvings. It is formed in the heartwood of Aquilaria Trees when they become infected with a type of mould (Phialophora Parasitica). Prior to infection, the heartwood is odourless, relatively light and pale coloured; however, as the infection progresses, the tree produces a dark aromatic resin, called Aloes or Agar (not to be confused with the edible, algae-derived Agar) as well as Gaharu, Jinko, Oud, or Oodh (not to be confused with Bukhoor), in response to the attack, which results in a very dense, dark, resin-embedded heartwood. The resin-embedded wood is valued in many cultures for its distinctive fragrance, and thus is used for incense and perfumes. The aromatic qualities of Agarwood are influenced by the species, geographic location, its branch, trunk and root origin, length of time since infection, and methods of harvesting and processing.
First-grade Agarwood is one of the most expensive natural raw materials, although in practice adulteration of the wood and oil is common. A whole range of qualities and products are on the market, varying in quality with geographical location, botanical species, the age of the specific tree, cultural deposition and the section of the tree where the piece of Agarwood stems from. Oud oil is distilled from Agarwood, and fetches high prices depending on the oil's purity.
The odour of Agarwood is complex and pleasing, with few or no similar natural analogues. In the perfume state, the scent is mainly distinguished by a combination of "oriental-woody" and "very soft fruity-floral" notes. The incense smoke is also characterized by a "sweet-balsamic" note and "shades of vanilla and musk" and amber (not to be confused with ambergris). As a result, Agarwood and its essential oil gained great cultural and religious significance in ancient civilizations around the world, being described as a fragrant product as early as 1400 BCE in one of the world's oldest written texts – the Sanskrit Vedas from India. Agarwood is highly revered in the seminal texts of Hinduism, Christianity, Buddhism, and Islam.