Geographic information system(GIS) apply computer technology to the tasks of capturing, storing, manipulating, analyzing, modeling, and displaying information about the surface of The Earth, and the phenomena distributed on it. They have emerged over the past three decades as a distinct form of computer use, with its own software industry and array of products, directed at application ranging from management of the resources of utility companies, to support for global change science. Worldwide sales of GIS software in the late Nineteen Nitees were in the region of $600Million annually, with much larger investments in associated digital geographic data.
GIS deal with information that is geographical or spatially or explicit, representing the spatial variation of phenomena over the Earth. Although many forms of software are capable of handling such information in limited ways, GIS is the only form designed expressly for this purpose, with a full range of necessary data structures and functions. Global changes science is also inherently geographically explicit, dealings with spatial dynamics and differentiation over the surface of the planet. Thus GIS is uniquely suitable as a tool for the computing functions needed to support global change science. It is often helpful to think of a GIS as a computer containing maps. One of the simplest reasons for manipulating maps with computers is to make them easier to construct and draw, and GIS are often used for this purpose. By computerizing the map-making process it is possible to edit easily, manipulate the map’s contents without the labor-intensive task of redrafting communicate maps electronically, and create output in any convenient form. The advent of GIS has made it possible for anyone to be a cartographer who is in possession of the necessary software a computer to run it on, and a suitable printing device. The view of a GIS as an automated mapping system is much too simplistic, however. The first GIS is generally agreed to have been Canada Geographic information system(CGIS), a project developed in the Canadian government in 1960s, under the direction of Roger Tomlinson .At the time there were no printers capable of making acceptable maps, even in black and white, and the design of CGIS did not include map output. Instead, the project was justified entirely on the basis of the need to analyze geographic information obtained from maps. Its original design include a through cost-benefit analysis that is still a model for the industry, and found substantial net benefits to computerization despite the high costs and crude technology of the time. The case for computerizing the analysis of geographic information rests on two propositions: first, that the few traditional tools that exist are very labor intensive and crude; and second, that once geographic information is in digital form there are massive scale economies because of the many forms of analysis that are possible.
Written by: Gull Rang Kakar