Aromatics originating from the resin-infused infected wood of the Aquilaria and Gyrinops genera have distinct and valued fragrances. Resin formation occurs as a response to internal injury and/or infections in the stems of the agarwood tree. The incenses and perfumes that are produced from agarwood have been valued for centuries and used by many cultures for spiritual, opulent, and aphrodisiac purposes. Agarwood is highly revered in the seminal texts of Hinduism, Christianity, Buddhism, and Islam. As early as 1400 B.C.E., agarwood was described as a fragrant product in Sanskrit texts, and in 65 B.C.E., Dioscorides detailed several medical applications for agarwood. Knowledge of human-induced agarwood formation was recorded in China as early as 300 C.E., where it was known that cutting into a tree would lead to a color change in its internal tissues within a year of the injury as a consequence of resin development. There is historical evidence of international trade in agarwood between the producing (tropical southeastern Asia) and consuming (Middle East, India, China, and Japan) regions of the world. Agarwood has been consumed primarily as incense with the burning of wood chips directly or as an important ingredient for powdered incense blends. The aromatic qualities of agarwood are influenced by the species and variety of the two genera, geographic location, its branch, trunk and root origin, length of time since infection, and methods of harvesting and processing. The subtle but numerous variations in agarwood properties led to the development of systems for product classification and description in several consumer countries. This paper reviews the uses and trade of agarwood and its social, political, and economic significance in human history.