XML

The Extensible Markup Language (short XML) is a markup language like HTML but is extensible.^[3] 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.

XML

Filename extension	.xml
Internet media type	application/xml[1] text/xml[2]
Uniform Type Identifier (UTI)	public.xml
UTI conformation	public.text
Developed by	World Wide Web Consortium
Type of format	Markup language
Extended from	SGML
Extended to	Numerous, including: XHTML, RSS, Atom, KML
Standard	1.0 (Fifth Edition) November 26, 2008; 16 years ago (2008-11-26) 1.1 (Second Edition) August 16, 2006; 18 years ago (2006-08-16)
Open format?	Yes

Some programs get information out of an XML-document. To do that, they need an API.^[4] There are many APIs for XML.JSON was built to replace this purpose of 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.

Syntax

XML uses less than (<) and greater than (>) to show tags. For example, a paragraph in HTML would be <p>.

A closing tag is a tag used to enclose the value of the tag. The tag has a slash (/) before its name. For example, </p>

A tag which is empty can be represented as an opening tag but with a slash before the >. For example, <p/> (or <p />)

The XML specification defines a valid XML document as a well-formed XML document which also conforms to the rules of a Document Type Definition (DTD).^[5][6]

Languages

The following languages are based on XML.

Text

• XSL-FO
• DocBook
• DITA
• XHTML (HTML based on ALL)
• TEI (Text Encoding Initiative)
• NITF (News Industry Text Format)

Images

• SVG (vector graphics)
• X3D (3D modelling language)
• Collada (Language to change informations between different 3D programs)

Earth

• 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

Multimedia

• SMIL (Informations with times from multimedia)
• MPEG-7 (for MPEG-7)
• Laszlo (LZX)

Safety

• SAML (describe and send informations about safety)
• XML Signature
• XML Encryption

Other

There are a lot more languages that use XML. A couple of them are:

• RSS
• WAP/WML