A geographic information system, or a GIS, is an information technology system that allows for the storage, manipulation, analysis, and display of information that has geographic component, also called geospatial data. A GIS allows for the visualization of multiple layers of geographic data to provide an easy means to present and interpret it. As well, complex spatial analysis and queries can be performed within and among data in a GIS to locate new trends and expose relationships.
GIS allows people to connect the information that they have about things or places with its physical location and develop an even better understanding of the subject. When we are able to give data a relatable location, we are able to draw relationship out of it, visualize it, and understand it in greater depth than would be possible without its geographic component.
You may or may not realize it, but GIS and geospatial data are being used everyday by people and groups around the world. Governments organization, large and small, use GIS to plan and document services and infrastructure; public health organizations use GIS to track epidemics, outbreaks, and health trends; conservation organizations use it to track wildlife migration patterns and identify critical habitats. Location services on cell phones, demographic information, outbreak locations, weather patterns, political boundaries, refugee camps, word pronunciations, popular foods, and many other types of information have, or can be enhanced with their geographic location, and any piece of information that has a geographic component can be integrated into GIS. As Jack Dangermond, a pioneer in GIS and the CEO of a leading GIS software company, Esri, has said "The application of GIS is limited only by the imagination of those who use it.”
Data types that have a spatial component are called geospatial data. Geospatial data exists in either one of two formats, vector or raster.
Vector data are datasets with explicit coordinates and are represented as points, lines, or polygon features. Point data is often referred to as simply "location data" because they represents a location in space. Features that have a length or distance, such as rivers and roads, are referred to as lines, while features with an area are called polygons. Polygons are used to represent regions such as parcels, cities, forests, states, or countries.
Rasters, or coverages, are images whose edges have been given a geographic location. While vector data is explicit, because rasters are composed of pixels, they represent average values within the area covered by the pixel. Rasters are often used in a GIS to show elevation, satellite images, or paper maps that have been scanned into a digital format and given geographic extents.
For more information about what GIS is, who uses it, and all of the things you can do with it. Check out some of the links below.