Low density, in real estate terms, describes the number of housing units per given unit of land in a particular area. Low density housing typically refers to residential areas occupied primarily by single-family homes or buildings with a small number of units. High density areas are typically urban areas with buildings that have a large number of units. Low density areas usually have more green space but do not have as much commercial space nearby. Most cities have low or high density zones, and the number of units allowed in each type of area is defined by the city. Suburban areas typically have more low density zones than urban areas; however, city and state laws can change, so owners and developers must stay abreast of any upcoming discussions of zoning changes.