A geographic information system (GIS) is a system used to describe and characterize the earth and other geographies for the purpose of visualizing and analyzing geographically referenced information.
Many have characterized GIS as one of the most powerful of all information technologies because it focuses on integrating knowledge from multiple sources (for example, as layers within a map) and creates a crosscutting environment for collaboration. In addition, GIS is attractive to most people who encounter it because it is both intuitive and cognitive. It combines a powerful visualization environment—using maps to communicate and visualize—with a strong analytic and modeling framework that is rooted in the science of geography.
This combination has resulted in a technology that is science based, trusted, and easily communicated using maps and other geographic views.
ArcGIS combines series of fundamental aspects of GIS:
ArcGIS models geographic information as a logical set of layers or themes. For example, a GIS can contain data layers for the following:
Geographic information layers such as those described here are represented using a few common GIS data structures:
Like map layers, GIS datasets are geographically referenced so that they overlay one another and can be located on the earth's surface.
See Overview of geographic information elements for more information about modeling and representing geographic information.
Each GIS includes a set of intelligent, interactive maps and other views (such as 3D globes) that show features and feature relationships on the earth's surface. Various map views of the underlying geographic information can be constructed and used as "windows into the geographic database" to support query, analysis, and editing of geographic information. Maps can also be used to access geographic modeling tools that are used to derive new information.
GIS maps are interactive and help to communicate vast amounts of information. You can reach "through" an interactive map to present any set of information that helps your end users meet their missions and do important work.
See How maps convey geographic information for more information about mapping and visualization.
GIS includes a large set of geoprocessing functions to take information from existing datasets, apply analytic functions, and write results into new result datasets. There are numerous spatial operators, such as the Buffer and Intersect tools shown here, that can be applied to GIS data.
Each geoprocessing tool takes existing information as input and derives a new result, which can be used in subsequent operations. This ability to string together a logical sequence of operations so that you can perform spatial analysis and automate data processing—all by assembling a model—is one of the key elements of GIS.