A rural community is an open area of land that has few homes or other buildings and not very many people. Rural communities are characterized by their small population size, but the exact population threshold used to differentiate rural and urban communities varies depending on the definition. The existence of multiple rural definitions reflects the reality that rural and urban are multidimensional concepts. Sometimes population density is the defining concern, while in other cases, it is geographic isolation. Rural communities can be clustered in the vicinity of urban areas, and they can encompass a wide variety of settlements, from densely settled small towns and large-lot housing subdivisions on the fringes of urban areas to more sparsely populated and remote areas. The U.S. Census Bureau defines rural as all population, housing, and territory not included within an urbanized area or urban cluster.