An oak is a tree or shrub in the genus Quercus of the beech family, Fagaceae. There are approximately 600 extant species of oaks. The common name “oak” also appears in the names of species in related genera, notably Lithocarpus, as well as in those of unrelated species such as Grevillea robusta and the Casuarinaceae. Oak wood has been used as a hardwood timber for thousands of years, yet it takes up to 150 years before the wood products from an oak tree can be used for construction. Modern uses for oak wood include homewares, flooring, wine barrels and firewood.