Brownfield refers to land that is abandoned or underutilized due to pollution from industrial use. The specific definition of brownfield land varies and is decided by policy makers and/or land developers within different countries. The main difference in definitions of whether a piece of land is considered a brownfield or not depends on the presence or absence of pollution. Overall, brownfield land is a site previously developed for industrial or commercial purposes and thus requires further development before reuse.

Examples of post industrial brownfield sites include abandoned factories, dry cleaning establishments, gas stations, etc. Typical contaminants include hydrocarbon spillages, solvents and pesticides, as well as heavy metals like lead, asbestos, petroleum, etc.

Many contaminated post-industrial brownfield sites sit unused because the cleaning costs may be more than the land is worth after redevelopment. Previously unknown underground wastes can increase the cost for study and clean-up. Depending on the contaminants and damage present adaptive re-use and disposal of a brownfield can require advanced and specialized appraisal analysis techniques.