KML, or Keyhole Markup Language, is an XML-based format used for representing geographic data in applications like Google Earth. It allows users to create and share maps, including points of interest, paths, and polygons, by defining their geographic coordinates and visual styles. KML files can be easily created and edited using text editors or specialized software. They support various features, such as adding images, 3D models, and time-based data, making them versatile for visualizing complex geographic information. KML is widely used in fields like geography, urban planning, and environmental science.