| Electronic Documents Markup: A brief explanation of what markup languages are and where they come from. |
| Microformats: Simple data formats built upon existing and widely adopted standards. Overview, specifications, events, and discussion. |
| Project Xanadu: The original hypertext project. Includes a history of the project and gives credit to the early developers of markup languages. |
| whatis.com: markup: A short definition. |
| 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. |