What does the term "overlay operation" refer to in GIS?

The term "overlay operation" in GIS refers to the process of comparing two or more layers of spatial data to derive new information. This operation is essential in GIS analysis as it allows users to analyze relationships between different datasets. For example, overlay operations could involve examining land use patterns in relation to water bodies, enabling the identification of areas prone to flooding or determining zoning regulations' impact on natural resources.

In an overlay operation, various geometric functions can be applied, such as intersection, union, and difference, facilitating complex analysis by combining attributes from different layers. This contributes to more informed decision-making and effective spatial planning.

The other options do not accurately define overlay operations in GIS. Changing the color of a map layer is more about visual representation than data analysis. Adding new records to GIS data relates to data management rather than comparing existing datasets, and removing redundant data pertains to data cleaning processes. Thus, the correct understanding of overlay operations is focused on comparison and analysis of multiple layers.