Electronic Documents Markup A brief explanation of what markup languages are and where they come from. http://www.cs.wpi.edu/~kal/elecdoc/EDmarkup.html

Project Xanadu The original hypertext project. Includes a history of the project and gives credit to the early developers of markup languages. http://www.xanadu.com/

whatis.com: markup A short definition. http://whatis.techtarget.com/definition/0,289893,sid9_gci212527,00.html

YAML Ain't Markup Language (YAML) A straightforward machine parsable data serialization format designed for human readability and interaction with scripting languages such as Perl and Python. http://yaml.org/

Webopedia - Data Formats Contains information about many data formats. http://webopedia.com/Data/Data_Formats/