A Superfund site is a location in the United States that has been contaminated by hazardous waste and is eligible for cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). These sites are identified by the Environmental Protection Agency (EPA) due to their potential risk to human health and the environment. The Superfund program aims to clean up these contaminated areas and restore them for safe use. Cleanup efforts can involve removing hazardous materials, treating contaminated soil and water, and monitoring the site to ensure it remains safe for the community and ecosystem.