Google Earth is a 3d virtual globe, map, geographical information system given as a free service and paid service by search engine giant Google. It was originally Earth viewer 3d, a software released by Keyhole Inc. which was later acquired by Google in 2004. After acquiring Keyhole Ince, Google renamed Earth viewer 3D as Google Earth (GE) and rereleased on 2005 and it was an instant success and became a trend setter to satellite mapping applications and services driving massive public attention.
GE is available as a free version and a paid version ( Pro version, requires $400 per year). GE is available in many platforms including Windows, Linux, FreeBSD, Mac OS, Mobile phones as a Java application, also on iPhone. Google released a browser plugin on 2008 which enabled browsers to display satellite maps in 3D by installing just a browser plugin.
GE creates a virtual 3D globe viewing experience by superimposing earth image resources obtained from satellite photography, aerial photography and GIS images. For most of the land 2D images only available obtained from vertical photography, which can not give proper 3D impression. For other parts of earth, 3D images of terrain and buildings are available obtained using NASA’s DEM (digital elevation model) technology.
GE has capability to superimpose other data which can be geographically interpreted like pollution, spread of drought, administrative information etc as layers over maps. Newest versions provide various layers giving useful information like tourist attractions, roads, administrative data etc. In 2006 Google added a new layer called geographic web which added Wikipedia articles and Panoramio images as layers. Recent versions of Google earth gives layers of Flikr images, YouTube videos, web cam images etc as selectable layer over Google Earth maps.