There are many markup languages designed to deliver a variety of content to a browser on the Internet.
Objective Internet markup languages
By the end of this page you will be able to:
Standard Generalised Markup Language (SGML)
SGML (Standard Generalized Markup Language) is a language for defining markup languages such as HTML and for specifying the rules for tagging elements in a document. More specifically, SGML is a metalanguage - (not a markup language) and is used to create or formally describe markup languages. Because of SGML's complex nature, HTML and XML were developed as simplified subsets for use on the Internet.
Extensible Markup Language (XML)
XML (Extensible Markup Language)is a markup language for documents allowing you to create your own custom tags, maintaining the documents structure and intent. XML is a simplified form of SGML and is designed for widespread use (not just the Internet).
Hypertext Markup Language (HTML)
HTML (Hypertext Markup Language) describes the structure and layout of webpages and is the language of the WWW. HTML was developed by scientist Tim Berners-Lee in 1990.
Extensible HTML (XHLML)
XHTML (Extensible HTML) is similar to HTML but conforms the standards of XML. These standards are:
- All tag and attribute names must be in lowercase
- "Empty" tags must be written with an extra slash at the end. (self closing)
- All tags must have an end tag
- Attributes must have a value
- Attribute values must be quoted.
Mathematical Markup Language (MathML)
MathML (Mathematical Markup Language) is an application of XML for describing mathematical notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web documents. It is a recommendation of the W3C math working group. (W3C 2009) 
Virtual Reality Markup Language (VRML)
VRML (Virtual Reality Modeling Language) is a language for describing three-dimensional ( 3-D ) image sequences and possible user interactions to go with them. Using VRML, you can build a sequence of visual images into Web settings with which a user can interact by viewing, moving, rotating, and otherwise interacting with an apparently 3-D scene.
Augmented Reality Mark-up Language (ARML)
Augmented reality (AR), which involves superimposing virtual objects and information on top of the real world, and may soon become universal on mobile phones. Already, iPhone users can view augmented directions--the Layar program superimposes information from Wikipedia, Twitter, and Flickr on real-world areas, and Wikitude augments tourist hotspots with tips from Wikipedia. Wikitude creator Mobilizy just announced a new AR language called Augmented Reality Mark-up Language (ARML)(Grifantini, 2009, Sep 23).
- Mathematical Markup Language (MathML) Version 3.0 W3C retrieved 16 October 2010 from http://www.w3.org/TR/2009/WD-MathML3-20090604/
- What is VRML? Retrieved 16 October 2010 from http://whatis.techtarget.com/definition/0,,sid9_gci214153,00.html
- Grifantini, K. (2009, Sep 23) What's Augmented Reality's Killer App?. Technology Review. MIT. Retrieved September 26, 2009 from http://www.technologyreview.com/computing/23515/