To answer such questions, GIS technology uses a process called buffering to determine the proximity relationship between features. The integration of different data layers involves a process called overlay. At its simplest, this could be a visual operation, but analytical operations require one or more data layers to be joined physically. This overlay, or spatial join, can integrate data on soils, slope, and vegetation, or land ownership with tax assessment. For many types of geographic operation the end result is best visualized as a map or graph.
Maps are very efficient at storing and communicating geographic information.
While cartographers have created maps for millennia, GIS provides new and exciting tools to extend the art and science of cartography. Map displays can be integrated with reports, three-dimensional views, photographic images, and other output, such as multimedia. The National Biological Services uses GIS to study and manage the Gap Analysis Program. Using the GIS they can visualize the ecosystem as a complete unit and display graphics of sensitive areas. The Bureau of Land Management uses GIS to manage the ecosystem for the Columbia River Basin.