Keyhole Markup Language (KML) is a form of XML notation for expressing geographic information in internet-based maps like Google Earth. A KML file specifies a set of geographic features that may include placemarks, images, polygons, COLLADA 3D modes, and text descriptions.

Both KML and KMZ file types are recognized and extracted automatically by Google Earth. Typically, KML documents are fairly large, so the compressed form KMZ is used.