Definition: Polygon overlay
UN - Geographic Information Systems
A GIS operation in which two polygon data layers are combined to create a new data layer. The output layer consists of the areas of intersection of both sets of input polygons. The attribute table of the new data layer contains the attributes from both input data sets. Polygon overlay is one of the fundamental GIS operations that is often used to integrate information from heterogeneous sources, such as demographic and environmental data.
United Nations, "Handbook on Geospatial Infrastructure in Support of Census Activities", Department of Economic and Social Affairs, Statistics Division, Studies in Methods, Series F No. 103, New York, 2009