markdown

This article relies on references to primary sources or sources affiliated with the subject, rather than references from independent authors and third-party publications. Please add citations from reliable sources. (February 2009)

This article's use of external links may not follow Wikipedia's policies or guidelines. Please improve this article by removing excessive or inappropriate external links, and converting useful links where appropriate into footnote references. (March 2012)

This article is written like a manual or guidebook. Please help rewrite this article from a descriptive, neutral point of view, and remove advice or instruction. (May 2010)

Markdown is a lightweight markup language, originally created by John Gruber and Aaron Swartz allowing people "to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML)".^[1] The language takes many cues from existing conventions for marking up plain text in email.

Markdown is also a Perl script written by Gruber, Markdown.pl, which converts marked-up text input to valid, well-formed XHTML or HTML and replaces left-pointing angle brackets ('<') and ampersands with their corresponding character entity references. It can be used as a standalone script, as a plugin for Blosxom or Movable Type, or as a text filter for BBEdit.^[1]

Markdown has since been re-implemented by others as a Perl module available on CPAN (Text::Markdown), and in a variety of other programming languages. It is distributed under a BSD-style license and is included with, or available as a plugin for, several content-management systems.^[2][3]

Syntax examples

This is not an exhaustive listing of Markdown's syntax, and in many cases multiple styles of syntax are available to accomplish a particular effect. See the full Markdown syntax for more information. Characters which are ordinarily interpreted by Markdown as formatting commands will instead be interpreted literally if preceded by a backslash; for example, the sequence '\*' would output an asterisk rather than beginning a span of emphasized text. Markdown also does not transform any text within a "raw" block-level XHTML element; thus it is possible to include sections of XHTML within a Markdown source document by wrapping them in block-level XHTML tags.

Paragraphs

A paragraph is one or more consecutive lines of text separated by one or more blank lines. Normal paragraphs should not be indented with spaces or tabs:

This is a paragraph. It has two sentences.

This is another paragraph. It also has 
two sentences.

Line return

Line breaks inserted in the text are removed from the final result: the web browser is in charge of breaking lines depending on the available space. To force a line break, insert two spaces at the end of the line.

Emphasized text

*emphasis* or _emphasis_  (e.g., italics)

**strong emphasis** or __strong emphasis__ (e.g., boldface)

Code

To include code (formatted in monospace font), you can either surround inline code with backticks (`), like in

Some text with `some code` inside,

or indent several lines of code by at least four spaces, as in:

    line 1 of code
    line 2 of code
    line 3 of code

The latter option makes Markdown retain all whitespace—as opposed to the usual behaviour, which, by removing line breaks and excess spaces, would break indentation and code layout.

Lists

* An item in a bulleted (unordered) list
    * A subitem, indented with 4 spaces
* Another item in a bulleted list

1. An item in an enumerated (ordered) list
2. Another item in an enumerated list

Headings

HTML headings are produced by placing a number of hashes before the header text corresponding to the level of heading desired (HTML offers six levels of headings), like so:

# First-level heading

#### Fourth-level heading

The first two heading levels also have an alternative syntax:

First-level heading
===================

Second-level heading
--------------------

Line Breaks

When you do want to insert a break tag using Markdown, you end a line with two or more spaces, then type return.
Ex:
def show_results
tag_br space space
end

Result:
def show_results

end

Blockquotes

> "This entire paragraph of text will be enclosed in an HTML blockquote element.
Blockquote elements are reflowable. You may arbitrarily
wrap the text to your liking, and it will all be parsed
into a single blockquote element."

The above would translate into the following HTML:

<blockquote><p>This entire paragraph of text will be enclosed in an HTML blockquote element. Blockquote 
elements are reflowable. You may arbitrarily wrap the text to your liking, and it will all
be parsed into a single blockquote element.</p></blockquote>

Links

Links may be included inline:

[link text here](link.address.here)
Ex. [Markdown](http://en.wikipedia.com/wiki/Markdown)

Alternatively, links can be placed in footnotes outside of the paragraph, being referenced with some sort of reference tag. For example, including the following inline:

[link text here][linkref]

would produce a link if the following showed up outside of the paragraph (or at the end of the document):

[linkref]: link.address.here "link title here"

Horizontal rules

Horizontal rules are created by placing three or more hyphens, asterisks, or underscores on a line by themselves. You may use spaces between the hyphens or asterisks. Each of the following lines will produce a horizontal rule:

* * *
***
*****
- - -
---------------------------------------

Editors

While Markdown is a minimal markup language and is easily read and edited with a normal text editor there are special designed editors which preview the files direct with styles. Below there is a list of editors available:

• Dillinger.io an online Markdown editor with live preview and extended linkage to GitHub and Dropbox
• iA Writer, a Markdown editor for Mac OS X and iOS.
• Mou, a Markdown editor for Mac OS X.
• Byword, a Markdown editor for Mac OS X.
• MarkdownPad, a full-featured Markdown editor for Windows.
• WMD, a Javascript "WYSIWYM" editor for Markdown (from AttackLab)
• PageDown, a Javascript "WYSIWYM" editor for Markdown (from StackOverflow)
• Texts, a "WYSIWYM" Markdown editor for Mac OS X and Windows

Implementations

Many people have implemented parsers and generators in different programming languages because it is easily read and written. Below there is a list sorted on programming language implementations.

C

• Sundown, a Markdown implementation in C.
• Discount, a C implementation of the Markdown markup language
• peg-markdown, an implementation of markdown in C, using a PEG (parsing expression grammar).

Java

• MarkdownJ the pure Java port of Markdown.
• pegdown, a pure-Java Markdown implementation based on a PEG parser
• MarkdownPapers, Java implementation based on a JavaCC parser
• Txtmark, another Markdown implementation written in Java

JavaScript

• uedit, a Javascript "WYSIWYM" editor for Markdown
• Discount, node.js bindings for the above C markdown library
• markdown, a Markdown parser for JavaScript/node.js
• marked, a fast Markdown parser

Lua

• markdown.lua, a Markdown implementation in Lua
• Lunamark, a markdown to HTML and LaTeX converter written in Lua, using a PEG grammar
• lua-discount, a binding to the Discount C library.

Perl

• Markdown.pl, Text::Markdown - Convert Markdown syntax to (X)HTML

PHP

• PHP Markdown and Markdown Extra
• Markdown Viewer for PHP, allows the viewing of a Mardown doc via a local PHP server (a wrapper for PHP Markdown)

Ruby

• Redcarpet, a Ruby library for Markdown processing, powered by the Sundown library
• RDiscount, a Ruby library for Markdown processing, powered by the Discount library
• BlueCloth, an implementation of Markdown in Ruby

Others

• MarkdownSharp, a slightly modified C# implementation of the Markdown markup language. Developed and used by Stack Overflow.
• Markdownr.com, a simple website to preview markdown in real time
• Knockoff, a Markdown implementation written in Scala using Parser Combinators
• Actuarius, another Markdown implementation written in Scala using Parser Combinators
• Pandoc, a universal document converter written in Haskell
• Markdown in Python, A Python implementation of Markdown
• Blackfriday, another Markdown implementation written in Go
• Misaka, a Python binding for Sundown.
• Markdown-clj, a Markdown parser in Clojure.

External links

• Official Markdown project at Daring Fireball
• Markdown Wiki
• Introduction to Markdown (tutorial)
• MultiMarkdown (Improved Markdown with more syntax-features and export-options than traditional Markdown)

See also

• Comparison of documentation generators
• Markdown extensions
• Org-mode has similar lightweight markup.
• reStructuredText is a similar lightweight markup.
• Textile, a similar lightweight markup language.
• MultiMarkdown is another improved Markdown with more syntax-features and export-options than traditional Markdown.
• Asciidoc another lightweight markup supporting many types of document.

References

1. ^ ^{a b} Markdown 1.0.1 readme source code "Daring Fireball - Markdown". 17-Dec-2004. http://daringfireball.net/projects/markdown/. 
2. ^ "MarsEdit 2.3 ties the knot with Tumblr support - Ars Technica". http://arstechnica.com/apple/news/2009/03/marsedit-23-ties-the-knot-with-tumblr-support.ars. Retrieved 2009-08-11. 
3. ^ "Review: Practical Django Projects - Ars Technica". http://arstechnica.com/open-source/news/2008/07/review-practical-django-projects.ars. Retrieved 2009-08-11.