This is probably the most asked question posed to those in the Geographic Information Systems (GIS) field and is probably the hardest to answer in a succinct and clear manner. GIS is a technological field that incorporates geographical features with tabular data in order to map, analyze, and assess real-world problems. The key word to this technology is Geography – this means that some portion of the data is spatial. In other words, data that is in some way referenced to locations on the earth. Coupled with this data is usually tabular data known as attribute data. Attribute data can be generally defined as additional information about each of the spatial features. An example of this would be schools. The actual location of the schools is the spatial data. Additional data such as the school name, level of education taught, student capacity would make up the attribute data. It is the partnership of these two data types that enables GIS to be such an effective problem solving tool through spatial analysis.
GIS operates on many levels. On the most basic level, geographic information systems technology is used as computer cartography, that is for straight forward mapping. The real power of GIS is through using spatial and statistical methods to analyze attribute and geographic information. The end result of the analysis can be derivative information, interpolated information or prioritized information.
GIS Versus Geospatial
There is an increasing trend to use the term geospatial instead of GIS. What is the difference between geospatial and GIS? Although some may use the terms interchangeably, there is a distinct difference between the two in that GIS refers more narrowly to the traditional definition of using layers of geographic data to produce spatial analysis and derivative maps. Geospatial is more broadly use to refer to all technologies and applications of geographic data. For example, popular social media sites such as Foursquare and Facebook use “check-ins” that allow their users the ability to geographically tag their statuses. While those applications are considered to be geospatial, they don’t fall underneath the stricter definition of what makes up a geographic information system. More: What’s is the Difference Between GIS and Geospatial?
Other quotes to answer “What is GIS?”
“In the strictest sense, a GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information, i.e. data identified according to their locations. Practitioners also regard the total GIS as including operating personnel and the data that go into the system.” ~ USGS“
A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on earth. GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps.” ~ ESRI
“GIS is an integrated system of computer hardware, software, and trained personnel linking topographic, demographic, utility, facility, image and other resource data that is geographically referenced.” ~ NASA
“A geographic information system is a special case of information systems where the database consists of observations on spatially distributed features, activities or events, which are definable in space as points, lines, or areas. A geographic information system manipulates data about these points, lines, and areas to retrieve data for ad hoc queries and analyses” (Kenneth Dueker,Portland State University, 1979).
GIS has already affected most of us in some way without us even realizing it. If you’ve ever using an Internet mapping program to find directions, congratulations, you’ve personally used GIS. The new supermarket chain on the corner was probably located using GIS to determine the most effective place to meet customer demand.