Keyhole Markup Language in the context of NASA WorldWind

NASA WorldWind is an open-source (released under the NOSA license and the Apache 2.0 license) virtual globe. According to the website, "WorldWind is an open source virtual globe API. WorldWind allows developers to quickly and easily create interactive visualizations of 3D globe, map and geographical information. Organizations around the world use WorldWind to monitor weather patterns, visualize cities and terrain, track vehicle movement, analyze geospatial data and educate humanity about the Earth." It was first developed by NASA in 2003 for use on personal computers and then further developed in concert with the open source community since 2004. As of 2017, a web-based version of WorldWind is available online. An Android version is also available.

The original version relied on .NET Framework, which ran only on Microsoft Windows. The more recent Java version, WorldWind Java, is cross platform, a software development kit (SDK) aimed at developers and, unlike the old .NET version, not a standalone virtual globe application in the style of Google Earth. The WorldWind Java version was awarded NASA Software of the Year in November 2009. The program overlays NASA and USGS satellite imagery, aerial photography, topographic maps, Keyhole Markup Language (KML) and Collada files.

Google Earth is a web and computer program created by Google that renders a 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users to see cities and landscapes from various angles. Users can explore the globe by entering addresses and coordinates, or by using a keyboard or mouse. The program can also be downloaded on a smartphone or tablet, using a touch screen or stylus to navigate. Users may use the program to add their own data using Keyhole Markup Language and upload them through various sources, such as forums or blogs. Google Earth is able to show various kinds of images overlaid on the surface of the Earth and is also a Web Map Service client. In 2019, Google revealed that Google Earth covers more than 97 percent of the world.

In addition to Earth navigation, Google Earth provides a series of other tools through the desktop application, including a measure distance tool. Additional globes for the Moon and Mars are available, as well as a tool for viewing the night sky. A flight simulator game is also included. Other features allow users to view photos from various places uploaded to Panoramio, information provided by Wikipedia on some locations, and Street View imagery. The web-based version of Google Earth also includes Voyager, a feature that periodically adds in-program tours, often presented by scientists and documentarians.