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. Markdown is widely used in blogging, instant messaging, online forums, collaborative software, documentation pages, and readme files.
|Internet media type|
|Uniform Type Identifier (UTI)|
|Developed by||John Gruber and Aaron Swartz|
|Initial release||March 19, 2004|
December 17, 2004
|Type of format||Open file format|
|Extended to||pandoc, MultiMarkdown, Markdown Extra, CommonMark, RMarkdown|
The initial description of Markdown 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.
Markdown was inspired by pre-existing conventions for marking up plain text in email and usenet posts, such as the earlier markup languages setext (c. 1992), Textile (c. 2002), and reStructuredText (c. 2002).
In 2002 Aaron Swartz created atx and referred to it as “the true structured text format”. Swartz and Gruber then worked together to create the Markdown language in 2004, with the goal of enabling people "to write using an easy-to-read and easy-to-write plain text format, optionally convert it to structurally valid XHTML (or HTML)."
Its 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,
Markdown.pl, which converts marked-up text input to valid, well-formed XHTML or HTML and replaces angle brackets (
>) and ampersands (
&) with their corresponding character entity references. 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 divergenceEdit
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 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 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."
Gruber avoided using curly braces in Markdown to unofficially reserve them for implementation-specific extensions.
|Internet media type|
|Uniform Type Identifier (UTI)||uncertain|
|Developed by||John MacFarlane, open source|
|Initial release||October 25, 2014|
June 19, 2021
|Type of format||Open file format|
|Extended to||GitHub Flavored Markdown|
From 2012, a group of people, including Jeff Atwood and John MacFarlane, launched what Atwood characterised as a standardisation 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." No 1.0 spec has since been released as major issues still remain unsolved. 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:
Websites like GitHub, Bitbucket, Reddit, Diaspora, Stack Exchange, OpenStreetMap and SourceForge use variants of Markdown to facilitate discussion between users. Markdown is also supported in a wide variety of apps and services, like Microsoft Teams chat and Discord messages.
GitHub Flavored MarkdownEdit
GitHub had been using its own variant of Markdown since as early as 2009, adding 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. GitHub also changed the parser used on their sites accordingly, 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 is a lightweight markup language based on Markdown implemented in PHP (originally), Python and Ruby. It adds features not available with plain Markdown syntax. Markdown Extra is supported in some content management systems such as, for example, Drupal and TYPO3.
Markdown Extra adds the following features to Markdown:
- Markdown markup inside HTML blocks
- Elements with id/class attribute
- "Fenced code blocks" that span multiple lines of code
- Definition lists
|Text using Markdown syntax||Corresponding HTML produced by a Markdown processor||Text viewed in a browser|
Heading ======= Sub-heading ----------- # Alternative heading # Paragraphs are separated by a blank line. Two spaces at the end of a line produce a line break.
<h1>Heading</h1> <h2>Sub-heading</h2> <h1>Alternative heading</h1> <p>Paragraphs are separated by a blank line.</p> <p>Two spaces at the end of a line<br /> produce a line break.</p>
Paragraphs are separated by a blank line.
Two spaces at the end of a line
Text attributes _italic_, **bold**, `monospace`. Horizontal rule: ---
<p>Text attributes <em>italic</em>, <strong>bold</strong>, <code>monospace</code>.</p> <p>Horizontal rule:</p> <hr />
|Text attributes italic, bold, |
Bullet lists nested within numbered list: 1. fruits * apple * banana 2. vegetables - carrot - broccoli
<p>Bullet lists nested within numbered list:</p> <ol> <li>fruits <ul> <li>apple</li> <li>banana</li> </ul></li> <li>vegetables <ul> <li>carrot</li> <li>broccoli</li> </ul></li> </ol>
|Bullet lists nested within numbered list:
A [link](http://example.com). ![Image](Icon-pictures.png "icon") > Markdown uses email-style characters for blockquoting. > > Multiple paragraphs need to be prepended individually. Most inline <abbr title="Hypertext Markup Language">HTML</abbr> tags are supported.
<p>A <a href="http://example.com">link</a>.</p> <p><img alt="Image" title="icon" src="Icon-pictures.png" /></p> <blockquote> <p>Markdown uses email-style characters for blockquoting.</p> <p>Multiple paragraphs need to be prepended individually.</p> </blockquote> <p>Most inline <abbr title="Hypertext Markup Language">HTML</abbr> tags are supported.</p>
Most inline HTML tags are supported.
Implementations of Markdown are available for over a dozen programming languages; in addition, many 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.
- JotterPad: an online WYSIWYG editor that supports Markdown and fountain
- Doxygen: a source code documentation generator which supports Markdown with extra features
- RStudio: an IDE for R. It provides a C++ wrapper function for a markdown variant called sundown
- GitHub Flavored Markdown (GFM) ignores underscores in words, and adds syntax highlighting, task lists, and tables
- Nextcloud Notes: the default app for taking notes on the Nextcloud platform supports formatting using Markdown
- Technically HTML description lists.
- Gruber, John (8 January 2014). "The Markdown File Extension". The Daring Fireball Company, LLC. Retrieved 27 March 2022.
Too late now, I suppose, but the only file extension I would endorse is “.markdown”, for the same reason offered by Hilton Lipschitz: We no longer live in a 8.3 world, so we should be using the most descriptive file extensions. It’s sad that all our operating systems rely on this stupid convention instead of the better creator code or a metadata model, but great that they now support longer file extensions.
- Leonard, Sean (March 2016). "The text/markdown Media Type". Request for Comments: 7763. Internet Engineering Task Force. Retrieved 27 March 2022.
This document registers the text/markdown media type for use with Markdown, a family of plain-text formatting syntaxes that optionally can be converted to formal markup languages such as HTML.
- Swartz, Aaron (2004-03-19). "Markdown". Aaron Swartz: The Weblog.
- Gruber, John. "Markdown". Daring Fireball. Archived from the original on 2004-04-02. Retrieved 2014-04-25.
- Markdown 1.0.1 readme source code "Daring Fireball – Markdown". 2004-12-17. Archived from the original on 2004-04-02.
- "Markdown: License". Daring Fireball. Retrieved 2014-04-25.
- Leonard, Sean (March 2016). "Guidance on Markdown: Design Philosophies, Stability Strategies, and Select Registrations". Request for Comments: 7764. Internet Engineering Task Force. Retrieved 27 March 2022.
This document elaborates upon the text/markdown media type for use with Markdown, a family of plain-text formatting syntaxes that optionally can be converted to formal markup languages such as HTML. Background information, local storage strategies, and additional syntax registrations are supplied.
- "RMarkdown Reference site".
- Markdown Syntax "Daring Fireball – Markdown – Syntax". 2013-06-13. “Readability, however, is emphasized above all else. A Markdown-formatted document should be publishable as-is, as plain text, without looking like it’s been marked up with tags or formatting instructions. While Markdown’s syntax has been influenced by several existing text-to-HTML filters — including Setext, atx, Textile, reStructuredText, Grutatext, and EtText — the single biggest source of inspiration for Markdown’s syntax is the format of plain text email.”
- "Daring Fireball: Introducing Markdown". daringfireball.net. Retrieved 2020-09-23.
- Atwood, Jeff (2012-10-25). "The Future of Markdown". CodingHorror.com. Retrieved 2014-04-25.
- "Un naufragio personal: The Grutatxt markup". triptico.com. Retrieved 2022-06-30.
- "EtText: Documentation: Using EtText". ettext.taint.org. Retrieved 2022-06-30.
- "Markdown Syntax Documentation". Daring Fireball.
- "GitHub Flavored Markdown Spec – Why is a spec needed?". github.github.com.
- "Babelmark 2 – Compare markdown implementations". Johnmacfarlane.net. Retrieved 2014-04-25.
- "Babelmark 3 – Compare Markdown Implementations". github.io. Retrieved 2017-12-10.
- "Babelmark 2 – FAQ". Johnmacfarlane.net. Retrieved 2014-04-25.
- Gruber, John [@gruber] (4 September 2014). "@tobie @espadrine @comex @wycats Because different sites (and people) have different needs. No one syntax would make all happy" (Tweet) – via Twitter.
- Gruber, John (19 May 2022). "Markdoc". Daring Fireball. Retrieved May 19, 2022.
I love their syntax extensions — very true to the spirit of Markdown. They use curly braces for their extensions; I’m not sure I ever made this clear, publicly, but I avoided using curly braces in Markdown itself — even though they are very tempting characters — to unofficially reserve them for implementation-specific extensions. Markdoc’s extensive use of curly braces for its syntax is exactly the sort of thing I was thinking about.
- "UTI of a CommonMark document". 12 April 2017.
- "CommonMark specification".
- "Markdown Community Page". GitHub. Retrieved 2014-04-25.
- "Standard Markdown is now Common Markdown". Jeff Atwood. 4 September 2014. Retrieved 2014-10-07.
- "Standard Markdown Becomes Common Markdown then CommonMark". InfoQ. Retrieved 2014-10-07.
- "CommonMark". Retrieved 20 Jun 2018.
The current version of the CommonMark spec is complete, and quite robust after a year of public feedback … but not quite final. With your help, we plan to announce a finalized 1.0 spec and test suite in 2019.
- "Issues we MUST resolve before 1.0 release [6 remaining]". CommonMark Discussion. 2015-07-26. Retrieved 2020-10-02.
- "Markdown Variants". IANA. 2016-03-28. Retrieved 2016-07-06.
- "GitHub Flavored Markdown Spec". GitHub. Retrieved 2020-06-11.
- "Reddit markdown primer. Or, how do you do all that fancy formatting in your comments, anyway?". Reddit.com. Retrieved 2013-03-29.
- "Markdown Editing Help". StackOverflow.com. Retrieved 2014-04-11.
- "SourceForge: Markdown Syntax Guide". SourceForge.net. Retrieved 2013-05-10.
- "Use Markdown formatting in Teams". Microsoft. Retrieved 2022-01-13.
- "Markdown Text 101 (Chat Formatting: Bold, Italic, Underline)". discord.com. Archived from the original on June 26, 2020.
- "Markdown Syntax Documentation". daringfireball.net.
- "Basic Syntax: Italic". The Markdown Guide. Matt Cone. Retrieved 27 March 2022.
To italicize text, add one asterisk or underscore before and after a word or phrase. To italicize the middle of a word for emphasis, add one asterisk without spaces around the letters.
- Tom Preston-Werner. "GitHub Flavored Markdown Examples". GitHub. Retrieved 2021-04-02.
- "A formal spec for GitHub Flavored Markdown". GitHub Engineering. 14 March 2017. Retrieved 16 Mar 2017.
- Fortin, Michel (2018). "PHP Markdown Extra". Michel Fortin website. Retrieved 2018-12-26.
- "Markdown editor for BUEditor". 4 December 2008.
- "Markdown for TYPO3 (markdown_content)". extensions.typo3.org.
- "PHP Markdown Extra". Michel Fortin.
- Dietrich, André. "LiaScript". liascript.github.io. Retrieved 2022-01-17.
- "W3C Community Page of Markdown Implementations". W3C Markdown Wiki. Retrieved 24 March 2016.
- "Markdown THrowdown – What happens when FOSS software gets corporate backing". Ars Technica. 2014-10-05.
- "Why You Need a WYSIWYG Editor When Writing in Markdown and Fountain". JotterPad Blog. 2020-11-17. Retrieved 2020-12-06.
- "Doxygen Manual: Markdown support".
- Allaire, J.J.; e.a. (2015-06-30). "Markdown.cpp". GitHub project RStudio. Retrieved 2016-07-07.
- "Writing on GitHub". help.github.com. GitHub, Inc. Retrieved 9 July 2014.
- R Markdown: The Definitive Guide.
- "Nextcloud Notes App". Nextcloud Apps. Retrieved 2022-02-18.
- Official website for original John Gruber markup