What is GIS?
GIS is an acronym for Geographic Information Systems. A GIS, as it's name infers, is a system for managing geographic data and its associated information.
GIS is a computer system capable of integrating, storing, editing, analyzing, and displaying geographically-referenced information. In a more general way, GIS is a "smart map" tool that allows users to make better decisions based on a "map". Traditionally, users think of GIS as a map. But, the map is simply an end-product of the GIS.
The power of GIS is in the database where attribute information is stored about each and every feature. A road segment is not simply a line on a map. A road segment is stored in GIS in real world coordinates with projection parameters that make it a geographic feature, not just a graphic. In GIS, that feature has information attached to it, such as street name, type, direction, jurisdiction, speed limit, etc. There may be one column of data associated with that line, or there could be hundreds of columns of data associated with that single linear feature. Geospatial data can be very complex, and very powerful.
Salem GIS includes 5 core components that work together: hardware, software, data, people and policy. All five components make the “system” work to perform and to produce the incredible visuals and map products that customers have come to expect from GIS.
What is GIS? (Description of GIS from gis.com)