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<h1>Markdown: Syntax</h1>
<ul id="ProjectSubmenu">
<li><a href="/projects/markdown/" title=
"Markdown Project Page">Main</a></li>
<li><a href="/projects/markdown/basics" title=
"Markdown Basics">Basics</a></li>
<li><a class="selected" title=
"Markdown Syntax Documentation">Syntax</a></li>
<li><a href="/projects/markdown/license" title=
"Pricing and License Information">License</a></li>
<li><a href="/projects/markdown/dingus" title=
"Online Markdown Web Form">Dingus</a></li>
</ul>
<ul>
<li><a href="#overview">Overview</a>
<ul>
<li><a href="#philosophy">Philosophy</a></li>
<li><a href="#html">Inline HTML</a></li>
<li><a href="#autoescape">Automatic Escaping for Special
Characters</a></li>
</ul>
</li>
<li><a href="#block">Block Elements</a>
<ul>
<li><a href="#p">Paragraphs and Line Breaks</a></li>
<li><a href="#header">Headers</a></li>
<li><a href="#blockquote">Blockquotes</a></li>
<li><a href="#list">Lists</a></li>
<li><a href="#precode">Code Blocks</a></li>
<li><a href="#hr">Horizontal Rules</a></li>
</ul>
</li>
<li><a href="#span">Span Elements</a>
<ul>
<li><a href="#link">Links</a></li>
<li><a href="#em">Emphasis</a></li>
<li><a href="#code">Code</a></li>
<li><a href="#img">Images</a></li>
</ul>
</li>
<li><a href="#misc">Miscellaneous</a>
<ul>
<li><a href="#backslash">Backslash Escapes</a></li>
<li><a href="#autolink">Automatic Links</a></li>
</ul>
</li>
</ul>
<p><strong>Note:</strong> This document is itself written using
Markdown; you can <a href="/projects/markdown/syntax.text">see the
source for it by adding '.text' to the URL</a>.</p>
<hr>
<h2 id="overview">Overview</h2>
<h3 id="philosophy">Philosophy</h3>
<p>Markdown is intended to be as easy-to-read and easy-to-write as
is feasible.</p>
<p>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
<a href=
"http://docutils.sourceforge.net/mirror/setext.html">Setext</a>,
<a href="http://www.aaronsw.com/2002/atx/">atx</a>, <a href=
"http://textism.com/tools/textile/">Textile</a>, <a href=
"http://docutils.sourceforge.net/rst.html">reStructuredText</a>,
<a href=
"http://www.triptico.com/software/grutatxt.html">Grutatext</a>, and
<a href="http://ettext.taint.org/doc/">EtText</a> -- the single
biggest source of inspiration for Markdown's syntax is the format
of plain text email.</p>
<p>To this end, Markdown's syntax is comprised entirely of
punctuation characters, which punctuation characters have been
carefully chosen so as to look like what they mean. E.g., asterisks
around a word actually look like *emphasis*. Markdown lists look
like, well, lists. Even blockquotes look like quoted passages of
text, assuming you've ever used email.</p>
<h3 id="html">Inline HTML</h3>
<p>Markdown's syntax is intended for one purpose: to be used as a
format for <em>writing</em> for the web.</p>
<p>Markdown is not a replacement for HTML, or even close to it. Its
syntax is very small, corresponding only to a very small subset of
HTML tags. The idea is <em>not</em> to create a syntax that makes
it easier to insert HTML tags. In my opinion, HTML tags are already
easy to insert. The idea for Markdown is to make it easy to read,
write, and edit prose. HTML is a <em>publishing</em> format;
Markdown is a <em>writing</em> format. Thus, Markdown's formatting
syntax only addresses issues that can be conveyed in plain
text.</p>
<p>For any markup that is not covered by Markdown's syntax, you
simply use HTML itself. There's no need to preface it or delimit it
to indicate that you're switching from Markdown to HTML; you just
use the tags.</p>
<p>The only restrictions are that block-level HTML elements -- e.g.
<code><div></code>, <code><table></code>,
<code><pre></code>, <code><p></code>, etc. -- must be
separated from surrounding content by blank lines, and the start
and end tags of the block should not be indented with tabs or
spaces. Markdown is smart enough not to add extra (unwanted)
<code><p></code> tags around HTML block-level tags.</p>
<p>For example, to add an HTML table to a Markdown article:</p>
<pre>
<code>This is a regular paragraph.
<table>
<tr>
<td>Foo</td>
</tr>
</table>
This is another regular paragraph.
</code>
</pre>
<p>Note that Markdown formatting syntax is not processed within
block-level HTML tags. E.g., you can't use Markdown-style
<code>*emphasis*</code> inside an HTML block.</p>
<p>Span-level HTML tags -- e.g. <code><span></code>,
<code><cite></code>, or <code><del></code> -- can be
used anywhere in a Markdown paragraph, list item, or header. If you
want, you can even use HTML tags instead of Markdown formatting;
e.g. if you'd prefer to use HTML <code><a></code> or
<code><img></code> tags instead of Markdown's link or image
syntax, go right ahead.</p>
<p>Unlike block-level HTML tags, Markdown syntax <em>is</em>
processed within span-level tags.</p>
<h3 id="autoescape">Automatic Escaping for Special Characters</h3>
<p>In HTML, there are two characters that demand special treatment:
<code><</code> and <code>&</code>. Left angle brackets are
used to start tags; ampersands are used to denote HTML entities. If
you want to use them as literal characters, you must escape them as
entities, e.g. <code>&lt;</code>, and
<code>&amp;</code>.</p>
<p>Ampersands in particular are bedeviling for web writers. If you
want to write about 'AT&T', you need to write
'<code>AT&amp;T</code>'. You even need to escape ampersands
within URLs. Thus, if you want to link to:</p>
<pre>
<code>http://images.google.com/images?num=30&q=larry+bird
</code>
</pre>
<p>you need to encode the URL as:</p>
<pre>
<code>http://images.google.com/images?num=30&amp;q=larry+bird
</code>
</pre>
<p>in your anchor tag <code>href</code> attribute. Needless to say,
this is easy to forget, and is probably the single most common
source of HTML validation errors in otherwise well-marked-up web
sites.</p>
<p>Markdown allows you to use these characters naturally, taking
care of all the necessary escaping for you. If you use an ampersand
as part of an HTML entity, it remains unchanged; otherwise it will
be translated into <code>&amp;</code>.</p>
<p>So, if you want to include a copyright symbol in your article,
you can write:</p>
<pre>
<code>&copy;
</code>
</pre>
<p>and Markdown will leave it alone. But if you write:</p>
<pre>
<code>AT&T
</code>
</pre>
<p>Markdown will translate it to:</p>
<pre>
<code>AT&amp;T
</code>
</pre>
<p>Similarly, because Markdown supports <a href="#html">inline
HTML</a>, if you use angle brackets as delimiters for HTML tags,
Markdown will treat them as such. But if you write:</p>
<pre>
<code>4 < 5
</code>
</pre>
<p>Markdown will translate it to:</p>
<pre>
<code>4 &lt; 5
</code>
</pre>
<p>However, inside Markdown code spans and blocks, angle brackets
and ampersands are <em>always</em> encoded automatically. This
makes it easy to use Markdown to write about HTML code. (As opposed
to raw HTML, which is a terrible format for writing about HTML
syntax, because every single <code><</code> and
<code>&</code> in your example code needs to be escaped.)</p>
<hr>
<h2 id="block">Block Elements</h2>
<h3 id="p">Paragraphs and Line Breaks</h3>
<p>A paragraph is simply one or more consecutive lines of text,
separated by one or more blank lines. (A blank line is any line
that looks like a blank line -- a line containing nothing but
spaces or tabs is considered blank.) Normal paragraphs should not
be intended with spaces or tabs.</p>
<p>The implication of the "one or more consecutive lines of text"
rule is that Markdown supports "hard-wrapped" text paragraphs. This
differs significantly from most other text-to-HTML formatters
(including Movable Type's "Convert Line Breaks" option) which
translate every line break character in a paragraph into a
<code><br /></code> tag.</p>
<p>When you <em>do</em> want to insert a <code><br /></code>
break tag using Markdown, you end a line with two or more spaces,
then type return.</p>
<p>Yes, this takes a tad more effort to create a <code><br
/></code>, but a simplistic "every line break is a <code><br
/></code>" rule wouldn't work for Markdown. Markdown's
email-style <a href="#blockquote">blockquoting</a> and
multi-paragraph <a href="#list">list items</a> work best -- and
look better -- when you format them with hard breaks.</p>
<h3 id="header">Headers</h3>
<p>Markdown supports two styles of headers, <a href=
"http://docutils.sourceforge.net/mirror/setext.html">Setext</a> and
<a href="http://www.aaronsw.com/2002/atx/">atx</a>.</p>
<p>Setext-style headers are "underlined" using equal signs (for
first-level headers) and dashes (for second-level headers). For
example:</p>
<pre>
<code>This is an H1
=============
This is an H2
-------------
</code>
</pre>
<p>Any number of underlining <code>=</code>'s or <code>-</code>'s
will work.</p>
<p>Atx-style headers use 1-6 hash characters at the start of the
line, corresponding to header levels 1-6. For example:</p>
<pre>
<code># This is an H1
## This is an H2
###### This is an H6
</code>
</pre>
<p>Optionally, you may "close" atx-style headers. This is purely
cosmetic -- you can use this if you think it looks better. The
closing hashes don't even need to match the number of hashes used
to open the header. (The number of opening hashes determines the
header level.) :</p>
<pre>
<code># This is an H1 #
## This is an H2 ##
### This is an H3 ######
</code>
</pre>
<h3 id="blockquote">Blockquotes</h3>
<p>Markdown uses email-style <code>></code> characters for
blockquoting. If you're familiar with quoting passages of text in
an email message, then you know how to create a blockquote in
Markdown. It looks best if you hard wrap the text and put a
<code>></code> before every line:</p>
<pre>
<code>> This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
> consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
> Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
>
> Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
> id sem consectetuer libero luctus adipiscing.
</code>
</pre>
<p>Markdown allows you to be lazy and only put the
<code>></code> before the first line of a hard-wrapped
paragraph:</p>
<pre>
<code>> This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
> Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
id sem consectetuer libero luctus adipiscing.
</code>
</pre>
<p>Blockquotes can be nested (i.e. a blockquote-in-a-blockquote) by
adding additional levels of <code>></code>:</p>
<pre>
<code>> This is the first level of quoting.
>
> > This is nested blockquote.
>
> Back to the first level.
</code>
</pre>
<p>Blockquotes can contain other Markdown elements, including
headers, lists, and code blocks:</p>
<pre>
<code>> ## This is a header.
>
> 1. This is the first list item.
> 2. This is the second list item.
>
> Here's some example code:
>
> return shell_exec("echo $input | $markdown_script");
</code>
</pre>
<p>Any decent text editor should make email-style quoting easy. For
example, with BBEdit, you can make a selection and choose Increase
Quote Level from the Text menu.</p>
<h3 id="list">Lists</h3>
<p>Markdown supports ordered (numbered) and unordered (bulleted)
lists.</p>
<p>Unordered lists use asterisks, pluses, and hyphens --
interchangably -- as list markers:</p>
<pre>
<code>* Red
* Green
* Blue
</code>
</pre>
<p>is equivalent to:</p>
<pre>
<code>+ Red
+ Green
+ Blue
</code>
</pre>
<p>and:</p>
<pre>
<code>- Red
- Green
- Blue
</code>
</pre>
<p>Ordered lists use numbers followed by periods:</p>
<pre>
<code>1. Bird
2. McHale
3. Parish
</code>
</pre>
<p>It's important to note that the actual numbers you use to mark
the list have no effect on the HTML output Markdown produces. The
HTML Markdown produces from the above list is:</p>
<pre>
<code><ol>
<li>Bird</li>
<li>McHale</li>
<li>Parish</li>
</ol>
</code>
</pre>
<p>If you instead wrote the list in Markdown like this:</p>
<pre>
<code>1. Bird
1. McHale
1. Parish
</code>
</pre>
<p>or even:</p>
<pre>
<code>3. Bird
1. McHale
8. Parish
</code>
</pre>
<p>you'd get the exact same HTML output. The point is, if you want
to, you can use ordinal numbers in your ordered Markdown lists, so
that the numbers in your source match the numbers in your published
HTML. But if you want to be lazy, you don't have to.</p>
<p>If you do use lazy list numbering, however, you should still
start the list with the number 1. At some point in the future,
Markdown may support starting ordered lists at an arbitrary
number.</p>
<p>List markers typically start at the left margin, but may be
indented by up to three spaces. List markers must be followed by
one or more spaces or a tab.</p>
<p>To make lists look nice, you can wrap items with hanging
indents:</p>
<pre>
<code>* Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
viverra nec, fringilla in, laoreet vitae, risus.
* Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
Suspendisse id sem consectetuer libero luctus adipiscing.
</code>
</pre>
<p>But if you want to be lazy, you don't have to:</p>
<pre>
<code>* Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
viverra nec, fringilla in, laoreet vitae, risus.
* Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
Suspendisse id sem consectetuer libero luctus adipiscing.
</code>
</pre>
<p>If list items are separated by blank lines, Markdown will wrap
the items in <code><p></code> tags in the HTML output. For
example, this input:</p>
<pre>
<code>* Bird
* Magic
</code>
</pre>
<p>will turn into:</p>
<pre>
<code><ul>
<li>Bird</li>
<li>Magic</li>
</ul>
</code>
</pre>
<p>But this:</p>
<pre>
<code>* Bird
* Magic
</code>
</pre>
<p>will turn into:</p>
<pre>
<code><ul>
<li><p>Bird</p></li>
<li><p>Magic</p></li>
</ul>
</code>
</pre>
<p>List items may consist of multiple paragraphs. Each subsequent
paragraph in a list item must be intended by either 4 spaces or one
tab:</p>
<pre>
<code>1. This is a list item with two paragraphs. Lorem ipsum dolor
sit amet, consectetuer adipiscing elit. Aliquam hendrerit
mi posuere lectus.
Vestibulum enim wisi, viverra nec, fringilla in, laoreet
vitae, risus. Donec sit amet nisl. Aliquam semper ipsum
sit amet velit.
2. Suspendisse id sem consectetuer libero luctus adipiscing.
</code>
</pre>
<p>It looks nice if you indent every line of the subsequent
paragraphs, but here again, Markdown will allow you to be lazy:</p>
<pre>
<code>* This is a list item with two paragraphs.
This is the second paragraph in the list item. You're
only required to indent the first line. Lorem ipsum dolor
sit amet, consectetuer adipiscing elit.
* Another item in the same list.
</code>
</pre>
<p>To put a blockquote within a list item, the blockquote's
<code>></code> delimiters need to be indented:</p>
<pre>
<code>* A list item with a blockquote:
> This is a blockquote
> inside a list item.
</code>
</pre>
<p>To put a code block within a list item, the code block needs to
be indented <em>twice</em> -- 8 spaces or two tabs:</p>
<pre>
<code>* A list item with a code block:
<code goes here>
</code>
</pre>
<p>It's worth noting that it's possible to trigger an ordered list
by accident, by writing something like this:</p>
<pre>
<code>1986. What a great season.
</code>
</pre>
<p>In other words, a <em>number-period-space</em> sequence at the
beginning of a line. To avoid this, you can backslash-escape the
period:</p>
<pre>
<code>1986\. What a great season.
</code>
</pre>
<h3 id="precode">Code Blocks</h3>
<p>Pre-formatted code blocks are used for writing about programming
or markup source code. Rather than forming normal paragraphs, the
lines of a code block are interpreted literally. Markdown wraps a
code block in both <code><pre></code> and
<code><code></code> tags.</p>
<p>To produce a code block in Markdown, simply indent every line of
the block by at least 4 spaces or 1 tab. For example, given this
input:</p>
<pre>
<code>This is a normal paragraph:
This is a code block.
</code>
</pre>
<p>Markdown will generate:</p>
<pre>
<code><p>This is a normal paragraph:</p>
<pre><code>This is a code block.
</code></pre>
</code>
</pre>
<p>One level of indentation -- 4 spaces or 1 tab -- is removed from
each line of the code block. For example, this:</p>
<pre>
<code>Here is an example of AppleScript:
tell application "Foo"
beep
end tell
</code>
</pre>
<p>will turn into:</p>
<pre>
<code><p>Here is an example of AppleScript:</p>
<pre><code>tell application "Foo"
beep
end tell
</code></pre>
</code>
</pre>
<p>A code block continues until it reaches a line that is not
indented (or the end of the article).</p>
<p>Within a code block, ampersands (<code>&</code>) and angle
brackets (<code><</code> and <code>></code>) are
automatically converted into HTML entities. This makes it very easy
to include example HTML source code using Markdown -- just paste it
and indent it, and Markdown will handle the hassle of encoding the
ampersands and angle brackets. For example, this:</p>
<pre>
<code> <div class="footer">
&copy; 2004 Foo Corporation
</div>
</code>
</pre>
<p>will turn into:</p>
<pre>
<code><pre><code>&lt;div class="footer"&gt;
&amp;copy; 2004 Foo Corporation
&lt;/div&gt;
</code></pre>
</code>
</pre>
<p>Regular Markdown syntax is not processed within code blocks.
E.g., asterisks are just literal asterisks within a code block.
This means it's also easy to use Markdown to write about Markdown's
own syntax.</p>
<h3 id="hr">Horizontal Rules</h3>
<p>You can produce a horizontal rule tag (<code><hr
/></code>) by placing three or more hyphens, asterisks, or
underscores on a line by themselves. If you wish, you may use
spaces between the hyphens or asterisks. Each of the following
lines will produce a horizontal rule:</p>
<pre>
<code>* * *
***
*****
- - -
---------------------------------------
_ _ _
</code>
</pre>
<hr>
<h2 id="span">Span Elements</h2>
<h3 id="link">Links</h3>
<p>Markdown supports two style of links: <em>inline</em> and
<em>reference</em>.</p>
<p>In both styles, the link text is delimited by [square
brackets].</p>
<p>To create an inline link, use a set of regular parentheses
immediately after the link text's closing square bracket. Inside
the parentheses, put the URL where you want the link to point,
along with an <em>optional</em> title for the link, surrounded in
quotes. For example:</p>
<pre>
<code>This is [an example](http://example.com/ "Title") inline link.
[This link](http://example.net/) has no title attribute.
</code>
</pre>
<p>Will produce:</p>
<pre>
<code><p>This is <a href="http://example.com/" title="Title">
an example</a> inline link.</p>
<p><a href="http://example.net/">This link</a> has no
title attribute.</p>
</code>
</pre>
<p>If you're referring to a local resource on the same server, you
can use relative paths:</p>
<pre>
<code>See my [About](/about/) page for details.
</code>
</pre>
<p>Reference-style links use a second set of square brackets,
inside which you place a label of your choosing to identify the
link:</p>
<pre>
<code>This is [an example][id] reference-style link.
</code>
</pre>
<p>You can optionally use a space to separate the sets of
brackets:</p>
<pre>
<code>This is [an example] [id] reference-style link.
</code>
</pre>
<p>Then, anywhere in the document, you define your link label like
this, on a line by itself:</p>
<pre>
<code>[id]: http://example.com/ "Optional Title Here"
</code>
</pre>
<p>That is:</p>
<ul>
<li>Square brackets containing the link identifier (optionally
indented from the left margin using up to three spaces);</li>
<li>followed by a colon;</li>
<li>followed by one or more spaces (or tabs);</li>
<li>followed by the URL for the link;</li>
<li>optionally followed by a title attribute for the link, enclosed
in double or single quotes.</li>
</ul>
<p>The link URL may, optionally, be surrounded by angle
brackets:</p>
<pre>
<code>[id]: <http://example.com/> "Optional Title Here"
</code>
</pre>
<p>You can put the title attribute on the next line and use extra
spaces or tabs for padding, which tends to look better with longer
URLs:</p>
<pre>
<code>[id]: http://example.com/longish/path/to/resource/here
"Optional Title Here"
</code>
</pre>
<p>Link definitions are only used for creating links during
Markdown processing, and are stripped from your document in the
HTML output.</p>
<p>Link definition names may constist of letters, numbers, spaces,
and punctuation -- but they are <em>not</em> case sensitive. E.g.
these two links:</p>
<pre>
<code>[link text][a]
[link text][A]
</code>
</pre>
<p>are equivalent.</p>
<p>The <em>implicit link name</em> shortcut allows you to omit the
name of the link, in which case the link text itself is used as the
name. Just use an empty set of square brackets -- e.g., to link the
word "Google" to the google.com web site, you could simply
write:</p>
<pre>
<code>[Google][]
</code>
</pre>
<p>And then define the link:</p>
<pre>
<code>[Google]: http://google.com/
</code>
</pre>
<p>Because link names may contain spaces, this shortcut even works
for multiple words in the link text:</p>
<pre>
<code>Visit [Daring Fireball][] for more information.
</code>
</pre>
<p>And then define the link:</p>
<pre>
<code>[Daring Fireball]: http://daringfireball.net/
</code>
</pre>
<p>Link definitions can be placed anywhere in your Markdown
document. I tend to put them immediately after each paragraph in
which they're used, but if you want, you can put them all at the
end of your document, sort of like footnotes.</p>
<p>Here's an example of reference links in action:</p>
<pre>
<code>I get 10 times more traffic from [Google] [1] than from
[Yahoo] [2] or [MSN] [3].
[1]: http://google.com/ "Google"
[2]: http://search.yahoo.com/ "Yahoo Search"
[3]: http://search.msn.com/ "MSN Search"
</code>
</pre>
<p>Using the implicit link name shortcut, you could instead
write:</p>
<pre>
<code>I get 10 times more traffic from [Google][] than from
[Yahoo][] or [MSN][].
[google]: http://google.com/ "Google"
[yahoo]: http://search.yahoo.com/ "Yahoo Search"
[msn]: http://search.msn.com/ "MSN Search"
</code>
</pre>
<p>Both of the above examples will produce the following HTML
output:</p>
<pre>
<code><p>I get 10 times more traffic from <a href="http://google.com/"
title="Google">Google</a> than from
<a href="http://search.yahoo.com/" title="Yahoo Search">Yahoo</a>
or <a href="http://search.msn.com/" title="MSN Search">MSN</a>.</p>
</code>
</pre>
<p>For comparison, here is the same paragraph written using
Markdown's inline link style:</p>
<pre>
<code>I get 10 times more traffic from [Google](http://google.com/ "Google")
than from [Yahoo](http://search.yahoo.com/ "Yahoo Search") or
[MSN](http://search.msn.com/ "MSN Search").
</code>
</pre>
<p>The point of reference-style links is not that they're easier to
write. The point is that with reference-style links, your document
source is vastly more readable. Compare the above examples: using
reference-style links, the paragraph itself is only 81 characters
long; with inline-style links, it's 176 characters; and as raw
HTML, it's 234 characters. In the raw HTML, there's more markup
than there is text.</p>
<p>With Markdown's reference-style links, a source document much
more closely resembles the final output, as rendered in a browser.
By allowing you to move the markup-related metadata out of the
paragraph, you can add links without interrupting the narrative
flow of your prose.</p>
<h3 id="em">Emphasis</h3>
<p>Markdown treats asterisks (<code>*</code>) and underscores
(<code>_</code>) as indicators of emphasis. Text wrapped with one
<code>*</code> or <code>_</code> will be wrapped with an HTML
<code><em></code> tag; double <code>*</code>'s or
<code>_</code>'s will be wrapped with an HTML
<code><strong></code> tag. E.g., this input:</p>
<pre>
<code>*single asterisks*
_single underscores_
**double asterisks**
__double underscores__
</code>
</pre>
<p>will produce:</p>
<pre>
<code><em>single asterisks</em>
<em>single underscores</em>
<strong>double asterisks</strong>
<strong>double underscores</strong>
</code>
</pre>
<p>You can use whichever style you prefer; the lone restriction is
that the same character must be used to open and close an emphasis
span.</p>
<p>Emphasis can be used in the middle of a word:</p>
<pre>
<code>un*fucking*believable
</code>
</pre>
<p>But if you surround an <code>*</code> or <code>_</code> with
spaces, it'll be treated as a literal asterisk or underscore.</p>
<p>To produce a literal asterisk or underscore at a position where
it would otherwise be used as an emphasis delimiter, you can
backslash escape it:</p>
<pre>
<code>\*this text is surrounded by literal asterisks\*
</code>
</pre>
<h3 id="code">Code</h3>
<p>To indicate a span of code, wrap it with backtick quotes
(<code>`</code>). Unlike a pre-formatted code block, a code span
indicates code within a normal paragraph. For example:</p>
<pre>
<code>Use the `printf()` function.
</code>
</pre>
<p>will produce:</p>
<pre>
<code><p>Use the <code>printf()</code> function.</p>
</code>
</pre>
<p>To include a literal backtick character within a code span, you
can use multiple backticks as the opening and closing
delimiters:</p>
<pre>
<code>``There is a literal backtick (`) here.``
</code>
</pre>
<p>which will produce this:</p>
<pre>
<code><p><code>There is a literal backtick (`) here.</code></p>
</code>
</pre>
<p>The backtick delimiters surrounding a code span may include
spaces -- one after the opening, one before the closing. This
allows you to place literal backtick characters at the beginning or
end of a code span:</p>
<pre>
<code>A single backtick in a code span: `` ` ``
A backtick-delimited string in a code span: `` `foo` ``
</code>
</pre>
<p>will produce:</p>
<pre>
<code><p>A single backtick in a code span: <code>`</code></p>
<p>A backtick-delimited string in a code span: <code>`foo`</code></p>
</code>
</pre>
<p>With a code span, ampersands and angle brackets are encoded as
HTML entities automatically, which makes it easy to include example
HTML tags. Markdown will turn this:</p>
<pre>
<code>Please don't use any `<blink>` tags.
</code>
</pre>
<p>into:</p>
<pre>
<code><p>Please don't use any <code>&lt;blink&gt;</code> tags.</p>
</code>
</pre>
<p>You can write this:</p>
<pre>
<code>`&#8212;` is the decimal-encoded equivalent of `&mdash;`.
</code>
</pre>
<p>to produce:</p>
<pre>
<code><p><code>&amp;#8212;</code> is the decimal-encoded
equivalent of <code>&amp;mdash;</code>.</p>
</code>
</pre>
<h3 id="img">Images</h3>
<p>Admittedly, it's fairly difficult to devise a "natural" syntax
for placing images into a plain text document format.</p>
<p>Markdown uses an image syntax that is intended to resemble the
syntax for links, allowing for two styles: <em>inline</em> and
<em>reference</em>.</p>
<p>Inline image syntax looks like this:</p>
<pre>
<code>
</code>
</pre>
<p>That is:</p>
<ul>
<li>An exclamation mark: <code>!</code>;</li>
<li>followed by a set of square brackets, containing the
<code>alt</code> attribute text for the image;</li>
<li>followed by a set of parentheses, containing the URL or path to
the image, and an optional <code>title</code> attribute enclosed in
double or single quotes.</li>
</ul>
<p>Reference-style image syntax looks like this:</p>
<pre>
<code>![Alt text][id]
</code>
</pre>
<p>Where "id" is the name of a defined image reference. Image
references are defined using syntax identical to link
references:</p>
<pre>
<code>[id]: url/to/image "Optional title attribute"
</code>
</pre>
<p>As of this writing, Markdown has no syntax for specifying the
dimensions of an image; if this is important to you, you can simply
use regular HTML <code><img></code> tags.</p>
<hr>
<h2 id="misc">Miscellaneous</h2>
<h3 id="autolink">Automatic Links</h3>
<p>Markdown supports a shortcut style for creating "automatic"
links for URLs and email addresses: simply surround the URL or
email address with angle brackets. What this means is that if you
want to show the actual text of a URL or email address, and also
have it be a clickable link, you can do this:</p>
<pre>
<code><http://example.com/>
</code>
</pre>
<p>Markdown will turn this into:</p>
<pre>
<code><a href="http://example.com/">http://example.com/</a>
</code>
</pre>
<p>Automatic links for email addresses work similarly, except that
Markdown will also perform a bit of randomized decimal and hex
entity-encoding to help obscure your address from
address-harvesting spambots. For example, Markdown will turn
this:</p>
<pre>
<code><address@example.com>
</code>
</pre>
<p>into something like this:</p>
<pre>
<code><a href="&#x6D;&#x61;i&#x6C;&#x74;&#x6F;:&#x61;&#x64;&#x64;&#x72;&#x65;
&#115;&#115;&#64;&#101;&#120;&#x61;&#109;&#x70;&#x6C;e&#x2E;&#99;&#111;
&#109;">&#x61;&#x64;&#x64;&#x72;&#x65;&#115;&#115;&#64;&#101;&#120;&#x61;
&#109;&#x70;&#x6C;e&#x2E;&#99;&#111;&#109;</a>
</code>
</pre>
<p>which will render in a browser as a clickable link to
"address@example.com".</p>
<p>(This sort of entity-encoding trick will indeed fool many, if
not most, address-harvesting bots, but it definitely won't fool all
of them. It's better than nothing, but an address published in this
way will probably eventually start receiving spam.)</p>
<h3 id="backslash">Backslash Escapes</h3>
<p>Markdown allows you to use backslash escapes to generate literal
characters which would otherwise have special meaning in Markdown's
formatting syntax. For example, if you wanted to surround a word
with literal asterisks (instead of an HTML <code><em></code>
tag), you can backslashes before the asterisks, like this:</p>
<pre>
<code>\*literal asterisks\*
</code>
</pre>
<p>Markdown provides backslash escapes for the following
characters:</p>
<pre>
<code>\ backslash
` backtick
* asterisk
_ underscore
{} curly braces
[] square brackets
() parentheses
# hash mark
+ plus sign
- minus sign (hyphen)
. dot
! exclamation mark
</code>
</pre>
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