What Is a KML File? Full Form, Definition and Purpose

KML stands for Keyhole Markup Language. It is an XML-based file format used to store and display geographic data — including points, lines, polygons, paths and image overlays — on maps and Earth browsers. The name comes from Keyhole Inc., the company that originally created the format before Google acquired it in 2004.

In 2008, KML became an official international standard under the Open Geospatial Consortium (OGC), making it one of the most widely adopted geospatial file formats in the world. It is supported natively by Google Earth, Google Maps, QGIS, ArcGIS, Mapbox, NASA WorldWind and dozens of other platforms.

A KML file contains geographic coordinates in latitude and longitude, together with optional attributes such as name, description, style, colour and altitude. When you open a KML file in a viewer like this one, the geometry renders on the map exactly where those coordinates sit on Earth.

How a KML File Is Structured

A KML file is plain-text XML. You can open it in any text editor. Coordinates are in longitude, latitude, altitude order — note that longitude comes before latitude in KML, which is the reverse of the common lat/lon convention.

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <Document>
    <name>My Area of Interest</name>
    <Placemark>
      <name>AOI Polygon</name>
      <Polygon>
        <outerBoundaryIs><LinearRing>
          <coordinates>
            55.30,25.20,0  55.50,25.20,0
            55.50,25.40,0  55.30,25.40,0  55.30,25.20,0
          </coordinates>
        </LinearRing></outerBoundaryIs>
      </Polygon>
    </Placemark>
  </Document>
</kml>

The core elements are Document (container for all features), Placemark (individual geographic feature), Polygon / LineString / Point (geometry type) and coordinates (the actual lon,lat,alt tuples separated by whitespace).

How to Create a KML or KMZ File

Tools That Open KML and KMZ Files

What Are KML Files Used For?

KML Files and Satellite Imagery — How They Work Together

When you order high-resolution satellite imagery, you need to define exactly which area of Earth to capture. That boundary is your Area of Interest, and the standard format for submitting it is KML or KMZ. You draw your polygon in Google Earth or QGIS, export it as KMZ, and send it to your satellite imagery provider. The coordinates in your file calculate the total area in km², set the tasking boundary and determine pricing.

XRTech Group accepts KML and KMZ for all satellite imagery orders — optical imagery at 30cm to 2m resolution, SAR satellite imagery for all-weather monitoring, hyperspectral satellite imagery for mineral and agricultural analysis, and multispectral satellite imagery for NDVI and land cover mapping. Archive imagery starts from $1 per km². Minimum order is 25 km². Learn more about buying satellite imagery →

KML AOI Tips for Satellite Imagery Orders

• Draw a tight polygon around your actual area rather than a large bounding box — you pay per km².
• Use a single closed polygon. Multiple disconnected polygons may be processed as separate orders.
• Ensure coordinates are in WGS 84 (EPSG:4326). KML requires decimal degree geographic coordinates.
• The last coordinate pair must match the first to form a closed ring.
• Archive minimum is 25 km². New satellite tasking minimum is 100 km².