Markdown

History

Markdown was inspired by pre-existing conventions for marking up plain text in email and usenet posts, such as the earlier markup languages setext (), Textile (), and reStructuredText ().

In 2002 Aaron Swartz created atx and referred to it as "the true structured text format". Gruber created the Markdown language in 2004 with Swartz as his "sounding board". The goal of the language was to enable people "to write using an easy-to-read and easy-to-write plain text format, optionally convert it to structurally valid XHTML (or HTML)".

Another key design goal was readability, that the language be readable as-is, without looking like it has been marked up with tags or formatting instructions, unlike text formatted with "heavier" markup languages, such as Rich Text Format (RTF), HTML, or even wikitext (each of which have obvious in-line tags and formatting instructions which can make the text more difficult for humans to read).

Gruber wrote a Perl script, , which converts marked-up text input to valid, well-formed XHTML or HTML, encoding angle brackets () and ampersands (), which would be misinterpreted as special characters in those languages. It can take the role of a standalone script, a plugin for Blosxom or a Movable Type, or of a text filter for BBEdit.

Rise and divergence

As Markdown's popularity grew rapidly, many Markdown implementations appeared, driven mostly by the need for additional features such as tables, footnotes, definition lists,Technically HTML description lists 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 and a Perl implementation for conversion to HTML.

At the same time, a number of ambiguities in the informal specification had attracted attention. These issues spurred the creation of tools such as Babelmark to compare the output of various implementations, and an effort by some developers of Markdown parsers for standardization. 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."

Gruber avoided using curly braces in Markdown to unofficially reserve them for implementation-specific extensions.

Standardization

In 2012, a group of people, including Jeff Atwood and John MacFarlane, launched what Atwood characterised as a standardization effort.

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".

In September 2014, Gruber objected to the usage of "Markdown" in the name of this effort and it was rebranded as "CommonMark". 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".

The finalized 1.0 spec has not been released, as major issues still remain unsolved.

Nonetheless, the following websites and projects have adopted CommonMark: Codeberg, Discourse, GitHub, GitLab, Reddit, Qt, Stack Exchange (Stack Overflow), and Swift.

In March 2016, two relevant informational Internet RFCs were published:

• introduced MIME type .
• discussed and registered the variants MultiMarkdown, GitHub Flavored Markdown (GFM), Pandoc, and Markdown Extra among others.

Variants

Websites like Bitbucket, Diaspora, Discord, GitHub, OpenStreetMap, Reddit, SourceForge and Stack Exchange use variants of Markdown to make discussions between users easier.

Depending on implementation, basic inline HTML tags may be supported.

Italic text may be implemented by _underscores_ or *single-asterisks*.

GitHub Flavored Markdown

GitHub had been using its own variant of Markdown since as early as 2009, which added support for additional formatting such as tables and nesting block content inside list elements, as well as GitHub-specific features such as auto-linking references to commits, issues, usernames, etc.

In 2017, GitHub released a formal specification of its GitHub Flavored Markdown (GFM) that is based on CommonMark. It is a strict superset of CommonMark, following its specification exactly except for tables, strikethrough, autolinks and task lists, which GFM adds as extensions.

Accordingly, GitHub also changed the parser used on their sites, which required that some documents be changed. For instance, GFM now requires that the hash symbol that creates a heading be separated from the heading text by a space character.

Markdown Extra

Markdown Extra is a lightweight markup language based on Markdown implemented in PHP (originally), Python and Ruby.{{cite web | access-date = 2018-12-26 | archive-date = 2021-01-17 | archive-url = https://web.archive.org/web/20210117015819/https://michelf.ca/projects/php-markdown/extra/ | url-status = live

• Markdown markup inside HTML blocks
• Elements with id/class attribute
• "Fenced code blocks" that span multiple lines of code
• Tables
• Definition lists
• Footnotes
• Abbreviations

Markdown Extra is supported in some content management systems such as Drupal, Grav (CMS), Textpattern CMS and TYPO3.

Examples

Implementations

Implementations of Markdown are available for over a dozen programming languages; in addition, many applications, platforms and frameworks support Markdown. For example, Markdown plugins exist for every major blogging platform.

While Markdown is a minimal markup language and is read and edited with a normal text editor, there are specially designed editors that preview the files with styles, which are available for all major platforms. Many general-purpose text and code editors have syntax highlighting plugins for Markdown built into them or available as optional download. Editors may feature a side-by-side preview window or render the code directly in a WYSIWYG fashion.

Explanatory notes

References

References

1. Gruber, John. (8 January 2014). "The Markdown File Extension". The Daring Fireball Company, LLC.
2. Leonard, Sean. (March 2016). "The text/markdown Media Type". Internet Engineering Task Force.
3. Swartz, Aaron. (2004-03-19). "Markdown". Aaron Swartz: The Weblog.
4. Gruber, John. "Markdown". [[Daring Fireball]].
5. Leonard, Sean. (March 2016). "Guidance on Markdown: Design Philosophies, Stability Strategies, and Select Registrations". Internet Engineering Task Force.
6. "RMarkdown Reference site".
7. "Markdown: License". Daring Fireball.
8. (6 March 2025). "Mistral adds a new API that turns any PDF document into an AI-ready Markdown file".
9. "Daring Fireball: Introducing Markdown".
10. "I should write about it, but it's painful. More or less: Aaron was my sounding board, my muse.".
11. (2004-12-17). "Daring Fireball – Markdown".
12. "Markdown Syntax Documentation". Daring Fireball.
13. "GitHub Flavored Markdown Spec – Why is a spec needed?".
14. "Babelmark 2 – Compare markdown implementations". Johnmacfarlane.net.
15. "Babelmark 3 – Compare Markdown Implementations". github.io.
16. "Babelmark 2 – FAQ". Johnmacfarlane.net.
17. Gruber, John. (4 September 2014). "@tobie @espadrine @comex @wycats Because different sites (and people) have different needs. No one syntax would make all happy.".
18. Gruber, John. (19 May 2022). "Markdoc".
19. (12 April 2017). "UTI of a CommonMark document".
20. "CommonMark specification".
21. Atwood, Jeff. (2012-10-25). "The Future of Markdown". CodingHorror.com.
22. "Markdown Community Page". GitHub.
23. (4 September 2014). "Standard Markdown is now Common Markdown". Jeff Atwood.
24. "Standard Markdown Becomes Common Markdown then CommonMark". InfoQ.
25. "CommonMark".
26. (2015-07-26). "Issues we MUST resolve before 1.0 release [6 remaining]".
27. (2016-03-28). "Markdown Variants". [[Internet Assigned Numbers Authority.
28. (2024-10-03). "Markdown Text 101 (Chat Formatting: Bold, Italic, Underline)".
29. "GitHub Flavored Markdown Spec". GitHub.
30. "Reddit markdown primer. Or, how do you do all that fancy formatting in your comments, anyway?". Reddit.
31. "SourceForge: Markdown Syntax Guide". [[SourceForge]].
32. "Markdown Editing Help". StackOverflow.com.
33. "Markdown Syntax Documentation".
34. "Basic Syntax: Italic". Matt Cone.
35. [[Tom Preston-Werner]]. "GitHub Flavored Markdown Examples".
36. (14 March 2017). "A formal spec for GitHub Flavored Markdown".
37. "PHP Markdown Extra".
38. (4 December 2008). "Markdown editor for BUEditor".
39. (2025-04-27). "Plugin: wet_textfilter_markdown".
40. "Markdown for TYPO3 (markdown_content)".
41. "W3C Community Page of Markdown Implementations".
42. Gilbertson, Scott. (October 5, 2014). "Markdown throwdown: What happens when FOSS software gets corporate backing?". [[Ars Technica]].