Markdown
Markdown[11] is a lightweight markup language for creating formatted text using a plain-text editor. John Gruber and Aaron Swartz[3][4] created Markdown in 2004 as a markup language that is intended to be easy to read in its source code form.[11] Markdown is widely used for blogging and instant messaging, and also used elsewhere in online forums, collaborative software, documentation pages, and readme files.
For the marketing term, see Price markdown.$_$_$DEEZ_NUTS#0__titleDEEZ_NUTS$_$_$
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$_$_$DEEZ_NUTS#0__call_to_action.textDEEZ_NUTS$_$_$The initial description of Markdown[12] 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.[13]
Rise and divergence[edit]
As Markdown's popularity grew rapidly, many Markdown implementations appeared, driven mostly by the need for additional features such as tables, footnotes, definition lists,[note 1] and Markdown inside HTML blocks.
The behavior of some of these diverged from the reference implementation, as Markdown was only characterised by an informal specification[16] and a Perl implementation for conversion to HTML.
At the same time, a number of ambiguities in the informal specification had attracted attention.[17] These issues spurred the creation of tools such as Babelmark[18][19] to compare the output of various implementations,[20] and an effort by some developers of Markdown parsers for standardisation. However, Gruber has argued that complete standardization would be a mistake: "Different sites (and people) have different needs. No one syntax would make all happy."[21]
Gruber avoided using curly braces in Markdown to unofficially reserve them for implementation-specific extensions.[22]
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Filename extensions
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Filename extensions
.md, .markdown[2]
text/markdown; variant=CommonMark[9]
uncertain[23]
public.plain-text
John MacFarlane, open source
October 25, 2014
June 19, 2021[24]
Markdown
GitHub Flavored Markdown
From 2012, a group of people, including Jeff Atwood and John MacFarlane, launched what Atwood characterised as a standardisation effort.[13] A community website now aims to "document various tools and resources available to document authors and developers, as well as implementors of the various Markdown implementations".[25] In September 2014, Gruber objected to the usage of "Markdown" in the name of this effort and it was rebranded as CommonMark.[26][27] CommonMark.org published several versions of a specification, reference implementation, test suite, and "[plans] to announce a finalized 1.0 spec and test suite in 2019."[28] No 1.0 spec has since been released as major issues still remain unsolved.[29] Nonetheless, the following websites and projects have adopted CommonMark: Discourse, GitHub, GitLab, Reddit, Qt, Stack Exchange (Stack Overflow), and Swift.
In March 2016 two relevant informational Internet RFCs were published:
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