Oak wood is a hardwood variety that is obtained from oak trees, which are native to the northern hemisphere. Oak trees are a diverse group, comprising around 600 species, with some being deciduous, shedding their leaves seasonally, and others being evergreen, retaining their foliage throughout the year. Oak can be expensive to buy, but this is offset by its many strengths. As oak is a slow growing wood compared to many others, it takes a long time to reach maturity, when it can be felled and used for timber. As it is slow to produce, this naturally drives up the cost.