Hyper-Text Markup Language (HTML)
HTML is a markup language used for structuring and presenting content for the World Wide Web and a core technology of the Internet.
Invented for Python documentation. Intended to read well in plain text as well as convert to various other formats including HTML and TeX. Reading well in plain text means that it
Org-mode is a note taking tool to be used with Emacs. It is geared towards authoring documents, taking note, keeping todo lists and planning projects, all in a simple text format.
An XML markup language designed for technical books, articles and documentation.
DokuWiki is a simple to use, and highly versatile open-source wiki software, that doesn't require a database.