Sandalwood is a class of woods from trees in the genus Santalum. The woods are heavy, yellow, and fine-grained, and, unlike many other aromatic woods, they retain their fragrance for decades. Sandalwood oil is extracted from the woods. Sandalwood is often cited as one of the most expensive woods in the world. Both the wood and the oil produce a distinctive fragrance that has been highly valued for centuries. Consequently, some species of these slow-growing trees have suffered over-harvesting in the past.

Santalum is a genus of woody flowering plants in the Santalaceae family, the best known and commercially valuable of which is the Indian sandalwood tree, S. album. Members of the genus are trees or shrubs. Most are root parasites which photosynthesize their own food, but tap the roots of other species for water and inorganic nutrients. Several species, most notably S. album, produce highly aromatic wood, used for scents and perfumes and for herbal medicine. About 25 known species range across the Indomalayan, Australasian, and Oceanian realms, from India through Malesia to the Pacific Islands, as far as Hawaiʻi and the Juan Fernández Islands off the coast of South America.