Keyhole Markup Language — an XML-based file format for representing geographic data, originally developed for Google Earth and now an OGC standard.
KML files describe geographic features — points, lines, polygons — along with their styling (colours, icons, labels) and descriptive information. KML is human-readable XML and is widely supported by mapping applications. KMZ is a compressed version of KML.
KML is particularly common for sharing geographic data with non-technical users because it can be opened directly in Google Earth and Google Maps. However, it is less suitable for large datasets or complex analysis than formats like GeoJSON or shapefiles.
Example: A conservation organization shares the boundaries of protected areas as a KML file. Volunteers can open the file in Google Earth to see the boundaries overlaid on satellite imagery, without needing GIS software.