KML is derived from Keyhole Markup Language. KML is an XML notation for geographic annotation and visualization of features for use in two-dimensional maps and three-dimensional Earth browsers used on the Internet. The KML file specifies a set of features (place marks, images, polygons, 3D models, textual descriptions, etc.) for display in applications such as Google Earth and Google Maps or any other geospatial software implementing the KML encoding. Positions are located using longitude and latitude as defined by the World Geodetic System of 1984 (WGS84). KML became an international standard of the Open Geospatial Consortium in 2008.
KMZ files are KML files that are compressed in the ZIP format (in compatibility mode for ZIP 2.0).