The Muroidea are a large superfamily of rodents, including mice, rats, voles, hamsters, gerbils, and many other relatives. They occupy a vast variety of habitats on every continent except Antarctica. Some authorities have placed all members of this group into a single family, Muridae, due to difficulties in determining how the subfamilies are related to one another. The following taxonomy is based on recent well-supported molecular phylogenies. The muroids are classified in six families, 19 subfamilies, around 280 genera, and at least 1300 species.