What Is GIS? (Geographic Information System)

Maps apps use GIS to analyze and display data

A compass, small globe and map are sitting on a table.

Asian Alphan/Getty Images

Whether you realize it or not, you’re probably already using GIS (Geographic Information System), which is integral to popular apps like Google Maps. GIS is technology that collects, tracks, and analyzes location data has changed the way we work, live, travel, and shop.

Transportation companies like Uber rely on GIS technology to provide ride sharing services.

What Is GIS?

GIS stands for Geographic Information System. A GIS is a collection of data, related to geographical location, that can be stored, manipulated, and analyzed. It includes maps and 3-D visualizations to help users understand the data more readily.

For example, hikers use global positioning system (GPS) devices, based on GIS information, to know their location and plot a course in unknown areas.

Who Uses GIS?

Individuals and businesses use GIS for a wide variety of purposes. For example, cities or other governmental organizations can use GIS technology to determine changes in traffic flow based on proposed land use changes.

It can be used by public safety officials to identify high-crime areas, or by climate scientists to track glacier movement. It is also used by professionals in many other industries, including retail, logistics, healthcare, agriculture, and utilities.

What Is GIS Used For?

GIS can be used in several important ways:

Showing locations. A school district, for example, might overlay a map of the community with locations of all the schools. Or you might share your location with friends, courtesy of GIS data.

Presenting quantities. To help with containment, a health district might map the locations of a disease outbreak and the number of people affected in each area. In fact, one of the earliest uses of GIS was in 1854, when British physician John Snow mapped a cholera outbreak in London, using symbols of local landmarks such as roads, and property and water lines. By representing the data in this way, he found that most cholera cases were near a water line.

This cholera outbreak was a major breakthrough in spatial analysis and public health, and the start of epidemiology (the study of the spread of disease).

Revealing change. Maps of a particular location and condition (such as the number of growth returning after a forest fire) can be developed at one point and then a later point to show change over time.

Wildfire locations with areas of growth
National Park Service

How Has GIS Evolved?

Prior to widespread use of computers, a GIS was developed using a method called sieve mapping. This method involved placing layers of information printed on transparent paper on a light table to identify overlapping objects.

Starting around 1960, computers started to be used to perform GIS functions more accurately. Early organizations such as the Canadian Geographic System (CGIS), the Ordnance Survey in the U.K., and the U.S. Census Bureau made extensive use of GIS.

From the 1970s to the 1990s, GIS software proliferated as computer power increased. The first GIS meeting happened in the U.K. in 1975, and the first conference hosted by prominent GIS software provider Esri was held in 1981.

After 1990, with ever-increasing use of computers, satellites, and data analysis techniques, the use of GIS took off, and grew into what it is now.

GIS data is gathered through a variety of methods that fall into two categories, raster data capture, or vector data capture.

How Is a GIS Developed?

Raster data capture refers to methods of data capture without physical contact with the geographical location. Examples include satellite imaging and aerial photography.

Vector data capture involves physical surveying techniques such as differential global positioning systems (DGPS), which improve the accuracy of GPS, and electronic total stations (ETS), which are electronic instruments that include a microprocessor, electronic data collector, and storage system; they are used to measure distances and angles. Vector data capture is more accurate, but also more time-consuming.