"GIS" is an acronym meaning Geographic Information System. A Geographic Information System is basically a computer based tool for mapping and analyzing geographic information. GIS can be thought of as a map on a computer but remember that it is more than just a map. It's possible to combine many maps or "layers" of information and then analyze and manipulate them to create a new map. These new maps are often used for making decisions about land use, resources, transportation, real estate, retailing, etc.
This ability to incorporate spatial data, manage it, analyze it, and answer spatial questions is the distinctive characteristic of a geographic information system. Map making and geographic analysis is not new, but GIS makes it possible to do this type of work faster and more efficiently because of the power and ease of using modern computers. It allows virtually anyone to create a map to help explain historic events, plan for the future, and predict outcomes. The following explains the three components of a Geographic Information System.
Geographic: This is the part of GIS that explains "spatially" where things are such as the location of nations, states, counties, cities, schools, roads, rivers, lakes, and the list can go on and on. Spatially means where on the earth's surface an object or feature is located. This can be as simple as the latitude and longitude of a feature. The geographic feature or object can be anything of interest.
Information: GIS information is the "data" or "attribute" information about specific features that we are interested in. The name of the feature, what the feature is, the location of the feature, and any other information that is important. An example could be the name of a city, where it is located, how big it is in square feet (area), its population, its population in the past, and any other information that is important.
System: The system in GIS is the computer and the software that is written to help people analyze the data, look at the data and combine it in various ways to show relationships or to create geographic models. A GIS can be made up of a variety of software and hardware tools, as long as they are integrated to provide a functional geographic data processing tool.