Wednesday, 18 July 2012

What is GIS?

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, GIS is used as computer cartography, i.e. mapping. The real power in 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 geospatial and GIS 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 GIS definition.

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 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.

Components of GIS

The next step in understanding GIS is to look at each area of GIS and how they work together.  These components are:
  • Hardware
  • Software
  • Data
  • People


Hardware comprises the equipment needed to support the many activities of GIS ranging from data collection to data analysis. The central piece of equipment is the workstation, which runs the GIS software and is the attachment point for ancillary equipment. Data collection efforts can also require the use of a digitizer for conversion of hard copy data to digital data and a GPS data logger to collect data in the field. The use of handheld field technology is also becoming an important data collection tool in GIS. With the advent of web-enabled GIS, web servers have also become an important piece of equipment for GIS.


Different types of software are important for GIS. Central to this is the GIS application package. Such software is essential for creating, editing and analyzing spatial and attribute data, therefore these packages contain a myriad of GIS functions inherent to them. Extensions or add-ons are software that extends the capabilities of the GIS software package. Component GIS software is the opposite of application software. Component GIS seeks to build software applications that meet a specific purpose and thus are limited in their spatial analysis capabilities. Utilities are stand-alone programs that perform a specific function. For example, a file format utility that converts from on type of GIS file to another. There is also web GISsoftware that helps serve data and interactive maps through Internet browsers.


Data is the core of any GIS. There are two primary types of data that are used in GIS: vector and raster data. A geodatabase is a database that is in some way referenced to locations on the earth. Geodatabases are grouped into two different types: vector and raster. Vector data is spatial data represented as points, lines and polygons.  Raster data is cell-based data such as aerial imagery and digital elevation models.  Coupled with this data is usually data known as attribute data.  Attribute data generally defined as additional information about each spatial feature housed in tabular format. Documentation of GIS datasets is known as metadata.  Metadata contains such information as the coordinate system, when the data was created, when it was last updated, who created it and how to contact them and definitions for any of the code attribute data.


Well-trained GIS professionals knowledgeable in spatial analysis and skilled in using GIS software are essential to the GIS process. There are three factors to the people component: education, career path, and networking. The right education is key; taking the right combination of classes.  Selecting the right type of GIS job is important.  A person highly skilled in GIS analysis should not seek a job as a GIS developer if they haven't taken the necessary programming classes.  Finally, continuous networking with other GIS professionals is essential for the exchange of ideas as well as a support community.

Further reading:

Article last updated: March 1, 2012.
Article first written: November 12, 1999.  

23 Responses to “What is GIS?” Leave a reply ›

  • Hi There,
    I guess it is very nice to know that you have so much information with accuracy on your webpage. I am a student in GPS-GIS modelling and I would love to be an integral part of your plan if you would like to involve someone remotely in your program - maybe a volunteer data clerk would be okay. Thanks so much. I am still on your webpage.
  • Please tell me two things concerning on GIS as folloows:-
    1) a multidIsciplinary of GIS
    2) a historical development of platform
  • The GIS is our future.
    GIS is serving our world, i hope every man kind, countries, governments and companies realize that...
  • The power of GIS can not be underestimated and easily understood such that every sector has come to embrace it.
  • I like much the subject of GIS. I'm a graduate from Ardhi University in Tanzania. currently I am working in Green Resouces Limited in the department of GIS and Mapping.
    Your notes are good and I am impresed on it,if you can send me some more materials please and books.
    And I want to do masters in Geospartial Information so i will be more advanced on it.
  • GIS is an information system used in the making of maps; it is information on the geography of the earth; it is using established resources and expounding with additional information and it is also used in several fields of research. In addition, it is used locally with the taxing entities of our county, such as the sanitation district, fire departments, etc.
  • I real enjoy your GIS notes, they are good but not enough to make a person real interested on GIS to understand much of it.What is real about this GIS! I mean where does it come from and its development with regard to its demand in the field of world spatial analysis,"it's purposes" I'm sure you can make it.
  • This is really fascinating to have a wonderful field of study like GIS which is focusing towards solving our world from dangers of degradation of our resources at an alarming rate.
    Am a student of Environmental Management at Makerere University but i look foward to Master in GIS as an open door to our technological future.
  • Am a student of Geography and environmental management in the university of Port Harcourt Nigeria. The notes here are very wonderful and simplified i have really gained a lot reading them. I would love to have books on GIS or journals to current happenings in GIS as i have no acess to textbooks.
  • hey!
    In regard to conceptualization of GIS,Why use the overhead projector?
    do we also have a standard defination of GIS?
    What is NOT a GIS? Since it is a system consisting of many aspects ie. its not just a map, softwares, hardwares, personell, etc.
    what is it then?
    otherwise, GIS is an intersting field to just ignore.
  • I am in employed in the GIS departnment and also student in GIS. I hope your web will be much of assistance to me.
  • I'm really fasinated about the current world where GIS is playing a central role in major areas of decision making. i must confess it's being very wonderful.
    I am a student of MGIS in University Of Lagos, Nigeria. I wish to request if possible, for materials like text book, CDs, journals and all sort related to GIS that will help me develop more on my academic pursuit from any quarter please. i can be reached through my mail - - anytime.Thanks
  • i really enjoy ur article on GIS but want to know if any developing counties can really benfited from GIS,and what are the chances of making it known to other countries to embak on.i am a graduate of geography and regional planning dept from Ambrose alli university but will go for my masters in GIS.thnk u
  • Everyday life will one day rotate on GIS.
    Because GIS soon if not now has the ability to explain the geograpical phenomenon and compares the past with the present so that the future will be predicted on easily.
    GIS as a science tool gives us an idea on which measures we ought take in order to mitigate the likely adverse phenomenon as a result of our interaction with nature.
  • very good website to learn about GIS.It's a very easieast way for learning to a beginer.
  • I'm currently working on a GIS project and seriously... this site Rocks!!!
    It nicely explaines the core aspects of GIS.
    For a beginner, it's good. But still leaves a lot to work upon for someone working the depths of the subject.
    I just hope to see some more information regarding the subject in the near future..
  • i m graguate in electrical engg: my project based on gis it really enjoy ur article on GIS but want to know if any developing counties can really benfited from GIS,and what are the chances of making it known to other countries .
  • You make a great point about the difficulty in defining GIS - it is like trying to define IT in a nutshell! It covers so many things and has so many uses that its difficult to pin it down to one thing.
    The number of uses for GIS data is constantly growing and I think with more location based services arriving on the scene we might see more comprehensive geodatabases giving us all a better and more complete picture of the world around us and bringing problems to the attention of the masses e.g. shrinking amazonian forests or melting ice shelfs.
  • It's interesting to see that despite the widespread use of location in a lot of apps now, the actual understanding of what GIS as a technical field is still missing.
  • I have read your notes on GIS keenly. My department of Geography, University of Yaounde 1, Cameroon is two years old in this sciences and technology even though students and lecturers as individuals have been exposed to these tools long ago. The notes gives an overall simplified view of our expectations on this domain. The knowledge gathered from the notes is very inspiring to novies even though the future of GIS is not highlighted.That is after GIS what next as was the picture before its discovery. Students and lecturers of my department and countrymen are just mad about GIS in their areas of specialisation and works but lack access to good and simplified material like these notes to go about it or discover more. Looking forward for more on GIS from your databank which may become our database. Thanks
  • I'm starting a course in GIS this year and was doing some research about it. I must say your website has given me the heads up I need to understand this exciting field. I'm looking forward to it and am sure your site is going to come in handy in my studies with explanations and other facts. Thanks.

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