What is GIS?
Geographic Information Systems (GIS) is a software program used to capture, store, manage, analyze and manipulate spatial data. Spatial data is any information you might store in a database that has a geographic location associated with it.
An example of this would be a list of restaurants and their accompanying addresses. With GIS it is possible to display graphically in cartographic format these spatial locations (addresses in this case) in your databases.
What enables this functionality is a link between the database and the cartographic interface. Whether it's a road project located on a two mile stretch of roadway, a transit stop located at a street intersection, or environmentally sensitive plant species scattered across a vacant lot, GIS has the capability to store this information in a database, and display its geographic location and/or coverage on a digital map.
Complex analysis can then be performed on the data including queries, buffer analysis, distance and area calculations, quantities calculations, etc. Additionally, several different layers of data can be brought together to provide for complex analysis.
An example of this would be bringing together the road project layer with the environmentally sensitive plant species layer to determine what plant species might potentially be impacted by the road project.