A geographic information system (GIS), or geographical information system, is any system that captures, stores, analyzes, manages, and presents data that are linked to a location.

A GIS map can combine many layers of information, enabling you to ask questions and interpret relationships between the different layers of data.

A digital map created by GIS may contain any of the following:

• Dots or points to represent features, such as cities.
• Lines to represent features, such as roads.
• Small areas to represent features, such as lakes.

The GIS information originates from a database that is linked to the map. It is this database of information that drives the display of the map. The database stores where the point is located, how long the road is, and even how many square miles a lake occupies. This enables the user to ask questions about the name of a location represented by a point, or driving directions between two locations. The database can contain a large amount of information about a particular feature on a map, allowing further inquiry and analysis between features.

The layers of information that are combined depends on your purpose. For example:

• Determining the best location for a new store.
• Analyzing environmental damage.
• Viewing similar crimes in a city to detect a pattern.

All of these questions can be answered through the use of a GIS.

Estimates show that 80% of all data has a spatial component. Maps are just another way to visualize data and GIS is another way to manipulate the visualization of that data.