Markdown is a lightweight markup language for creating formatted text using a plain-text editor. John Gruber and Aaron Swartz created Markdown in 2004 as a markup language that is appealing to human readers in its source code form.[9] Markdown is widely used in blogging, instant messaging, online forums, collaborative software, documentation pages, and readme files.
The initial description of Markdown[10] contained ambiguities and raised unanswered questions, causing implementations to both intentionally and accidentally diverge from the original version. This was addressed in 2014, when long-standing Markdown contributors released CommonMark, an unambiguous specification and test suite for Markdown.[11]