As of 2015, Google Earth Pro is free and people can use the license key "GEPFREE" to access the software. Users do not require a serial number. People can download Google Earth Pro at Google.com. The software previously cost $399 per year and was initially intended for commercial use.
Google Earth displays satellite images of the planet's surface. It lets users view cities and houses from a bird's eye point of view. The software maps the Earth by superimposing images obtained from aerial photography, satellite imagery and geographical information systems.
The quality of resolution depends on the popularity of the featured location. The software uses 2D images for large parts of the Earth's surface. It uses 3D images of some buildings and terrain, such as Mount Everest.
The software also includes Google Street View, which allows users to view selected cities at ground level. This includes 40 U.S. cities and several suburbs. Street View also features major cities in other countries, such as Mexico, Canada, Japan, Sweden and the United Kingdom.
Google Earth evolved from a program called EarthViewer 3D, which was created by Keyhole Inc., a company funded by the Central Intelligence Agency. Google acquired Keyhole Inc. in 2004.