A Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. In other words, GIS describes any information system that integrates stores, edits, analyses, shares and displays geographic information for informing decision making.

A GIS can be described as a system that provides spatial data entry, management and retrieval, analysis and visualization functions. GIS applications are tools that allow users to create interactive queries (user-created searches), analyze spatial information, edit data in maps and present the results of all these operations.

The acronym GIS is sometimes used for Geographical Information Science or Geospatial Information Studies to refer to the academic discipline or career of working with geographical information systems and is a large domain within the broader academic discipline of Geoinformatics.

Geographic Information Science is the science underlying geographic concepts, applications and systems.

The first known use of the term Geographic Information System was by Dr Roger Tomlinson in the year 1968 in his paper “A Geographic Information System for Region Planning” in Ottawa, Onatario in Canada. Dr Roger Tomlinson is popularly referred to as the Father of GIS.



GIS is a relatively broad term that can refer to a number of different technologies, process and methods. It is attached to many operations and has many applications in the following ways:

  1. Engineering: The GIS is popularly used in the field of engineering by many scientists.
  2. Planning: The GIS is usually used by urban and regional planners in towns and cities.
  3. Management: It is also found to be used popularly in offices and organization in taking management decisions.
  4. Transport or Logistics: The GIS is equally used by transporters in enabling them to draw out certain logistics in transportation system.
  5. Insurance: The GIS is also found to be useful in the insurance sector of the economy. It enables the experts in insurance sub-sector to take critical decision in making their insurance business.
  6. Telecommunication: The GIS is also found to be useful in the field of telecommunication sub-sector of the economy.
  7. Business: Critical business decisions and management are made possible through the use of GIS in companies, organizations and government establishments.



Geographic data refers to any data which possess locational characteristics. In other words, it refers to a group of data which can be collated and analyzed in order to generate some basic geographical information.



Geographical data is found to be useful in the following ways:

  1. City Planning: Data collated and analyzed are often used for planning of cities.
  2. Flood Prediction: Certain data collected and analyzed can be better tools for flood prediction.
  3. Emergency Service Routing: Data are also found to be very useful in ensuring service routing in emergency cases.
  4. Environmental assessments: Data collated and analyzed are often used in monitoring certain parameters of the environment.
  5. Wind pattern monitoring: Useful geographic data are also used to monitor the pattern of wind movement in certain environment.



The Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze and manage data. While geographic data refers to a group of data which can be collated and analyze in order to generate some basic geographical information.



Examples of Geographic Data are:

  1. Lines for Rivers.
  2. Lines for Roads.
  3. Lines for Rails.
  4. Points for buildings.
  5. Points for Boreholes.
  6. Points for Settlements.
  7. Point for Towns.
  8. Points for Farmlands.



Geographical data can be obtained from the following sources. These are:

  1. Satellite Images.
  2. Existing Maps.
  3. Land Surveys.
  4. Socio-economic statistical records.
  5. Photograph-metric surveys.
  6. Aerial Photographs.
  7. Field works or surveys.



Geo-Referencing is defined as the process of scaling, rotating and translating an image to match a particular size and position. It is related to assigning coordinates to points on the image of known object. In summary, Geo-Referencing also involves the scanning of maps, aerial photographs and satellite images and drafting with the aid of a computer.



  1. Geo-Referencing is crucial to making aerial and satellite imagery, usually raster images, useful for mapping as it explains how other date relate to the imagery.
  2. Geo-Referencing also helps to determine the actual location of a place.
  3. Geo-Referencing also provides support for the raster data format that is a geo-referenced grid or numbers that can be used as reference.
  4. Different maps may use different projection system. Geo-referencing tools contain methods to combine and overlay these maps with minimum distortion.
  5. Geo-Referencing is also used to determine the scale and orientation of a map.
  6. Geo-Referencing is also useful in air travels as it helps in determining the position and direction of places.
  7. Very essential information may be contained in data or images that were produced at different point of time. It may be desired either to combine or compare this data with that currently available.
  8. Using Geo-Referencing methods, data obtained from surveying tools like total stations may be given a point of reference from topographic maps already available.