Sequoia sempervirens (pronounced /sɨˈkɔɪ.ə sɛmpərˈvaɪrənz/) is the sole living species of the genus Sequoia in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, California redwood, and giant redwood. It is an evergreen, long-lived, monoecious tree living 1200–1800 years or more. This species includes the tallest trees on Earth, reaching up to 379 feet (115.5 m) in height (without the roots) and up to 26 feet (7.9 m) diameter at breast height. Before commercial logging and clearing began by the 1850s, this massive tree occurred naturally in an estimated 2,100,000 acres (8,500 km²) along much of coastal California (excluding southern California where rainfall is not sufficient) and the southwestern corner of coastal Oregon within the United States. It is estimated that more than 95% of the original old-growth redwood forest has been cut down, due to its excellent properties for use as lumber in construction.

The name sequoia sometimes refers to the subfamily Sequoioideae, which includes S. sempervirens along with Sequoiadendron (giant sequoia) and Metasequoia (dawn redwood). On its own, the term redwood usually refers to the coast redwood, which is covered in this article, and not to the other two species.