Keyhole Markup Language (KML) is an XML-base language schema for expressing geographic annotation and visualization on existing or future Web-based, two-dimensional maps and three-dimensional Earth browsers. KML was developed for use with Google Earth, which was originally named Keyhole Earth Viewer. It was created by Keyhole, Inc, which was acquired by Google in 2004. The name "Keyhole" is an homage to the KH reconnaissance satellites, the original eye-in-the-sky military reconnaissance system first launched in 1976.