The Extensible Markup Language (short XML) is a computer language. It is a markup language like HTML but is extensible. It's created by the World Wide Web Consortium (W3C). XML defines rules for the construction of a document. XML adds context to the information in a document. It does not say how this should be displayed.
Some programs get information out of an XML-document. To do that, they need an API. There are many APIs for XML.
You can write a description of an XML document in a way that is useful for programmers. There are several languages for this; the best known is called DTD.
The following languages are based on XML.
- XHTML (HTML based on XML)
- TEI (Text Encoding Initiative)
- NITF (News Industry Text Format)
- SVG (vector graphics)
- X3D (3D modelling language)
- Collada (Language to change informations between different 3D programs)
- Geography Markup Language (GML)
- GPS Exchange Format (GPX): XML for GPS informatons
- Keyhole Markup Language (KML): coordinates for Google Earth
- OpenImmo : XML for Houses with position informations
There are a lot more languages that use XML. A couple of them are: