Brownfield: Abandoned and idle industrial and commercial sites in cities and other urban areas sometimes characterized by environmental degradation and contamination. The term "brownfield" is used to distinguish these sites from "greenfields," undeveloped land outside of cities and urban areas.

Built-up land: Land that has been physically altered through the construction of commercial, industrial, or residential buildings as well as roads, airports, and other infrastructure.

Central city: Large urbanized area that is the dominant employment and population center for a large, usually multi-county, region. Ann Arbor, for example, is the central city for its metropolitan area which includes Lenawee, Livingston, and Washtenaw counties. This differs from the Central Business District, or CBD, which represents an individual city's commercial center, often its downtown.

Edge cities: Large concentration of economic activity and development, usually spread out over many jurisdictions, without a traditional central city core or centralized downtown.

In-fill: Vacant or otherwise undeveloped land in urbanized areas, available for re-development.

Inner-ring suburbs: Cities representing the "first wave" of suburbanization beyond central city boundaries. While often considered "bedroom" communities, inner-ring suburbs have grown to include a mix of housing, commercial, and industrial land uses.

Low-density development: Land development that averages one housing unit per half-acre. Usually, this term is applied to single-family residential development on large lots.

Metropolitan statistical area: A region, often including more than one county based on commute and work patterns, defined by the U. S. Bureau of the Census as having a central city of at least 50,000 people or an urbanized area of 50,000 people and a metropolitan area population of at least 100,000 people.

Outer-ring suburbs: Cities and towns located beyond inner-ring suburbs where most residents commute outside their town of residence for work.

Purchase of development rights (PDR): The act of buying the legal right to develop property in the future by another private party, nonprofit organization, or government.

Suburban counties: Counties that do not include large central cities but are included in a metropolitan area defined by the U.S. Bureau of the Census. Also referred to as "collar" counties.

Urbanized area: Area with a population density of more than 1,000 people per square mile (1.56 people per acre) and connected to a "place." An urbanized "place" must have a minimum population of 2,500 people.