Geoprocessing

Geoprocessing is a Geographic Information Systems (GIS) term used to describe any of the various processes in which specialized software tools are used to compare, analyze, or manipulate map layers and their underlying geographic data to create new sets of data. Geoprocessing yields relationships about geographic information that would otherwise be difficult to visualize or interpret in a geographic context. Working in tandem with selection tools that select by attribute or by location, geoprocessing software tools (GP tools) provide a wide array of quantitative and qualitative analysis and functionality that is core to the value of using a GIS.

Basic Geoprocessing
The concept of geoprocessing is fundamental to GIS, and includes traditional areas of geographic analysis such as overlay and proximity analysis based on selected map features, topology processing, raster processing, and data conversion. Common GIS analysis functions that are geoprocessing include:
 * Buffer
 * Clip
 * Dissolve
 * Intersect
 * Merge
 * Union

Overlay Analysis
Overlay analysis is a common, widely used method of analyzing and evaluating geospatial data. Overlay analysis utilizes map layers in a GIS to discover relationships across the layers. Overlay analysis is used to investigate geographic patterns and to determine locations that meet specific criteria. The criteria is typically defined in queries.

Geoprocessing in ArcGIS Desktop
A wide variety of geoprocessing tools are available in ArcGIS Desktop, and more are added with each release of the software (there are currently over 700 available in ArcGIS Desktop 10). These tools perform tasks ranging from format conversions to 3D Unions.