Geographic Information System (GIS) is a computer based information system used to digitally represent and analyse the geographic features present on the Earth' surface and the events (non-spatial attributes linked to the geography under study) that taking place on it. The meaning to represent digitally is to convert analog (smooth line) into a digital form.

"Every object present on the Earth can be geo-referenced", is the fundamental key of associating any database to GIS. Here, term 'database' is a collection of information about things and their relationship to each other and 'geo-referencing' refers to the location of a layer or coverage in space defined by the co-ordinate referencing system.

GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable to a wide range of public and private enterprises for explaining events, predicting outcomes, and planning strategies. (ESRI).

Need of GIS?
Many professionals, such as foresters, urban planners, and geologists, have recognized the importance of spatial dimensions in organising & analysing information. Whether a discipline is concerned with the very practical aspects of business, or is concerned with purely academic research, geographic information system can introduce a perspective, which can provide valuable insights as

70% of the information has geographic location as its denominator making spatial analysis an essential tool. Ability to assimilate divergent sources of data both spatial and non-spatial (attribute data). Visualization Impact Analytical Capability Sharing of Information

Major areas of application

• Different streams of planning
  Urban planning, housing, transportation planning architectural conservation, urban design, landscape.
  
• Street Network Based Application
  It is an addressed matched application, vehicle routing and scheduling: location and site selection and disaster planning.
  
• Natural Resource Based Application
  Management and environmental impact analysis of wild and scenic recreational resources, flood plain, wetlands, acquifers, forests, and wildlife.
  
• View Shed Analysis
  Hazardous or toxic factories siting and ground water modelling. Wild life habitat study and migrational route planning.
  
• Land Parcel Based
  Zoning, sub-division plans review, land acquisition, environment impact analysis, nature quality management and maintenance etc.
  
• Automated Mapping/ Facilities Management
  Can locate underground pipes and cables for maintenance, planning, tracking energy use.