What is GIS?
It may seem odd to still be discussing “what is GIS” nowadays, given the fact that GIS has now passed its 50th birthday. But, considering that GIS has evolved in many ways and will continue to do even more rapidly in terms of its functionality, platform, data, application areas, audience, and social context, perhaps we continually need to revisit what it is. In addition, GIS is also at the same time, a set of tools, an approach to understanding the world, a discipline, and part of other disciplines such as geodesign and GIScience. Furthermore, new audiences are continually discovering GIS and applying it to new fields and problems. Yes, it does make sense that such a topic needs to be defined and understood.
As is most likely the case with you reading this essay, I so firmly believe in the power of GIS to make our world more efficient, healthier, and happier, and I never tire of talking with people about what GIS is. I do so wherever I have the opportunity—in workshops, presentations, courses, books, and even in everyday life such as on airport shuttles, community functions, and on elevators. I encourage you to work on your “elevator speech” if you don’t already have one, as I have here and here.
Another way of introducing people to the definition of GIS is through a video. These videos have been important teaching resources going back to Roger Tomlinson’s Data for Decisions films from 1967 through today. Besides that of Dr. Tomlinson, some of my favorites are those from Esri, Rebekah Jones, GIS Videos TV, and Esri Ireland. but I also recently created my own video on the topic with my own interpretation of what GIS is, and why it matters to education and society.
Many of us remember the core GIS definitions from our university textbooks, which usually included the following: GIS is composed of hardware, software, data, methods (tools, models, and procedures), and people. Another useful and oft-cited definition is, “GIS is a system for collecting, management, manipulation, analysis, and presentation of spatially referenced data.” Still another definition is that a GIS enables us to help capture, model, store, manage, and present complex systems.
Another way to conceptualize GIS—Geographic Information Systems—is to break apart its three words: The “G” or “Geographic” component refers to the location-component that GIS has—everything in a GIS is referenced to real-world coordinates. These coordinates can define a single point, or a line or polygon. They can also define the starting point and extent of a grid, or image. The “I” or “Information” component refers to the informational database behind the spatial data; a geo-database, usually stored as a table or set of related tables, containing spatial fields (such as latitude-longitude or street address or city names), and aspatial fields (such as housing type or number of people between 10 and 19 years old). The “S” or “System” component ties the “G” and the “I” segments together—one can select a feature via using the map, or via a row in the data table. The “S” component ensures that a GIS is not just a set of graphics floating around in cyberspace, but that the attributes are always linked to the mapped feature.
By combining the spatial with the aspatial data, we create a holistic view of the world. GIS data are analyzed in layers, which can cover such themes as land use, land cover, hydrography, zoning, ecoregions, transportation, elevation, climate, and more.
The process-oriented definition of GIS is that: A GIS is a computer-based system that provides for the collection, storage, analysis, and display of georeferenced data. A problem-solving definition of GIS is: A GIS is a decision support system involving the integration of spatially referenced data in a problem-solving environment.
GIS is sometimes defined in terms of the questions it can answer, including:
Location: What is at………….? This question seeks to find out what exists at a particular location. A location can be described in many ways, using, for example place name, post code, or geographic reference such as longitude/latitude.
Condition: Where is it………….? The second question is the converse of the first and requires spatial data to answer. Instead of identifying what exists at a given location, one may wish to find location(s) where certain conditions are satisfied (such as an unforested section of at-least 2000 square meters in size, within 100 meters of road, and with soils suitable for supporting buildings).
Aspatial Questions: "What's the average number of people working with GIS in each location?" is an aspatial question - the answer to which does not require the stored value of latitude and longitude; nor does it describe where the places are in relation with each other.
Spatial Questions. "How many people work with GIS in the major neighborhoods or centers of Delhi" OR " Which centers lie within 10 km of each other? ", OR " What is the shortest route passing through all these centers". These are spatial questions that can only be answered using latitude and longitude data and other information such as the radius of the Earth. GIS can answer such questions.
More recently, some presentations have focused on GIS moving from a system of record to a system of engagement.
Each of these definitions has its place—they all help us conceptualize what GIS is and contribute to the richness of its evolving nature. My own definitions as I speak about in this video are as follows:
GIS is part of the geotechnologies. Back in 2004, the US Department of Labor identified three hot, key, growing fields for the 21st Century: Nanotechnologies, biotechnologies, and geotechnologies. GIS, along with GPS, web mapping, and remote sensing, are part of the geotechnologies. Some people and programs prefer the terms geodata, location analytics, geoinformatics, or geomatics.
GIS is all about solving spatial problems in our world from local to global scale. Thus, it is an application of geography. Spatial problems all have to do with the “where” question. Where are the fire hydrants in my community? Where do natural hazards occur and how do they affect communities? How could sea level rise impact coastal lands? Energy, water, migration, biodiversity loss, sustainable agriculture, human health, city planning, and other issues of our 21st Century world can be better understood and solved using GIS.
GIS is composed of several key elements—hardware, software (which is increasingly on the web), spatial data (also increasingly on the web) including real-time feeds, tools, methods, and people. People apply GIS in decision-making environments, in nonprofit organizations, private industry, academia, and government organizations to make a positive difference in our world by solving problems.
GIS is a key technology for our world, as increasing pressure exists on the environment through resource use and population. GIS is all about critical thinking, spatial thinking, and making our world more sustainable, healthier, and happier.
A few of my other videos about GIS include its application to education and geography, and reflecting on GIS at a giant cube, why GIS is better than paper maps, my TED talk on mapping, and making every day GIS day.
What is the definition of GIS that you find to be most useful? How do you think GIS will change in the coming years?