GIS (Geographical Information System) is a computer support system that represents data using maps. It helps people access, display and analyse data that has geographic content and meaning. For those not familiar with GIS, it used to be a niche IT market dominated by the traditional GIS and CAD companies such as Intergraph, Bentley, MapInfo, Autodesk and ESRI. Nowadays global IT giants such as Microsoft, Google and Oracle are competing for their share of the pie through products such as Virtual Earth, Google Earth and Oracle Spatial. NASA has also recently released a free, open source GIS viewer application called World Wind.-GIS (Geographical Information System) is a computer support system that represents data using maps. It helps people access, display and analyze data that has geographic co ntent and meaning. For those not familiar with G. IS, it used to be a niche IT market dominated by the tr aditional GIS and CAD companies such as Intergr aph, Bentley, and MapInfo. Autodesk and ESRI. Nowadays global IT giants su ch as Microsoft. Google and Oracle are competing for their share of the pie through products such as Virtual Eart h Google Earth and Oracle Spatial. NASA has also r ecently released a free, open source GIS viewer application called Worl d Wind.