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WHAT is GIS? A Geographic Information System, or GIS, is a computer-based approach to collecting, storing, and analyzing data that have spatial characteristics. A GIS can be thought of as a collection of electronic maps, stored in a computer database, that allows a wide range of analysis and product generation. A GIS stores data that are primarily geographical in nature. Geography, as defined by Webster's University Dictionary, is the study of the earth and its features and the distribution of life on the earth. A GIS stores information about these subjects including the location and other detailed descriptions or attributes. Capturing and storing the location of things or events on the surface of the earth allows the GIS to display and analyze spatial relationships. The spatial locations in a GIS are simply defined by X,Y coordinates such as latitude and longitude. Spatial locations can show where the features are located and also define the shape of the feature. Geographic data usually have one of three basic forms; a point, a line, or a polygon. Points have a single coordinate location and can represent a feature such as a bird nest. Lines have a starting and ending location, and points in between that describe their shape. A stream or highway may be represented in the GIS as a line. The last shape data can take is a polygon. A polygon is formed when a line defines a closed shape. Examples of polygon features include lakes or real estate parcels. For more information on GIS, see www.gis.com. OTHER GIS MAPPING LINKS Pierce County Thurston County - GeoData King County King County “about ARCIMS presentation”