KML files are “Keyhole Markup Language” files which contain geographic information for display in software such as Google Earth and within Google Maps.

Google Earth reads both KML files and their compressed equivalent, KMZ, which uses the ZIP compression algorithm. KMZ files also can contain other resources, such as models of structures keyed to ...

But, let me describe the fundamentals. KML stands for Keyhole Markup Language (Keyhole was the name of the application before Google bought it and added their own features and larger databases).