A brownfield is a previously developed property that may be contaminated by hazardous substances, pollutants, or other environmental contamination from past industrial or commercial use. Examples include former gas stations, factories, dry cleaners, and industrial yards. Brownfields present both challenges and opportunities—contamination makes them difficult and expensive to redevelop, but they are often well-located in urban areas with existing infrastructure. Cleaning up brownfields (remediation) removes environmental hazards and returns land to productive use. Government programs at various levels offer incentives for brownfield redevelopment, recognizing that reusing these sites reduces sprawl and revitalizes communities.