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0001 Markdown: Syntax
0002 ================
0003 
0004 <ul id="ProjectSubmenu">
0005     <li><a href="/projects/markdown/" title="Markdown Project Page">Main</a></li>
0006     <li><a href="/projects/markdown/basics" title="Markdown Basics">Basics</a></li>
0007     <li><a class="selected" title="Markdown Syntax Documentation">Syntax</a></li>
0008     <li><a href="/projects/markdown/license" title="Pricing and License Information">License</a></li>
0009     <li><a href="/projects/markdown/dingus" title="Online Markdown Web Form">Dingus</a></li>
0010 </ul>
0011 
0012 
0013 *   [Overview](#overview)
0014     *   [Philosophy](#philosophy)
0015     *   [Inline HTML](#html)
0016     *   [Automatic Escaping for Special Characters](#autoescape)
0017 *   [Block Elements](#block)
0018     *   [Paragraphs and Line Breaks](#p)
0019     *   [Headers](#header)
0020     *   [Blockquotes](#blockquote)
0021     *   [Lists](#list)
0022     *   [Code Blocks](#precode)
0023     *   [Horizontal Rules](#hr)
0024 *   [Span Elements](#span)
0025     *   [Links](#link)
0026     *   [Emphasis](#em)
0027     *   [Code](#code)
0028     *   [Images](#img)
0029 *   [Miscellaneous](#misc)
0030     *   [Backslash Escapes](#backslash)
0031     *   [Automatic Links](#autolink)
0032 
0033 
0034 **Note:** This document is itself written using Markdown; you
0035 can [see the source for it by adding '.text' to the URL][src].
0036 
0037   [src]: /projects/markdown/syntax.text
0038 
0039 * * *
0040 
0041 <h2 id="overview">Overview</h2>
0042 
0043 <h3 id="philosophy">Philosophy</h3>
0044 
0045 Markdown is intended to be as easy-to-read and easy-to-write as is feasible.
0046 
0047 Readability, however, is emphasized above all else. A Markdown-formatted
0048 document should be publishable as-is, as plain text, without looking
0049 like it's been marked up with tags or formatting instructions. While
0050 Markdown's syntax has been influenced by several existing text-to-HTML
0051 filters -- including [Setext] [1], [atx] [2], [Textile] [3], [reStructuredText] [4],
0052 [Grutatext] [5], and [EtText] [6] -- the single biggest source of
0053 inspiration for Markdown's syntax is the format of plain text email.
0054 
0055   [1]: http://docutils.sourceforge.net/mirror/setext.html
0056   [2]: http://www.aaronsw.com/2002/atx/
0057   [3]: http://textism.com/tools/textile/
0058   [4]: http://docutils.sourceforge.net/rst.html
0059   [5]: http://www.triptico.com/software/grutatxt.html
0060   [6]: http://ettext.taint.org/doc/
0061 
0062 To this end, Markdown's syntax is comprised entirely of punctuation
0063 characters, which punctuation characters have been carefully chosen so
0064 as to look like what they mean. E.g., asterisks around a word actually
0065 look like \*emphasis\*. Markdown lists look like, well, lists. Even
0066 blockquotes look like quoted passages of text, assuming you've ever
0067 used email.
0068 
0069 
0070 
0071 <h3 id="html">Inline HTML</h3>
0072 
0073 Markdown's syntax is intended for one purpose: to be used as a
0074 format for *writing* for the web.
0075 
0076 Markdown is not a replacement for HTML, or even close to it. Its
0077 syntax is very small, corresponding only to a very small subset of
0078 HTML tags. The idea is *not* to create a syntax that makes it easier
0079 to insert HTML tags. In my opinion, HTML tags are already easy to
0080 insert. The idea for Markdown is to make it easy to read, write, and
0081 edit prose. HTML is a *publishing* format; Markdown is a *writing*
0082 format. Thus, Markdown's formatting syntax only addresses issues that
0083 can be conveyed in plain text.
0084 
0085 For any markup that is not covered by Markdown's syntax, you simply
0086 use HTML itself. There's no need to preface it or delimit it to
0087 indicate that you're switching from Markdown to HTML; you just use
0088 the tags.
0089 
0090 The only restrictions are that block-level HTML elements -- e.g. `<div>`,
0091 `<table>`, `<pre>`, `<p>`, etc. -- must be separated from surrounding
0092 content by blank lines, and the start and end tags of the block should
0093 not be indented with tabs or spaces. Markdown is smart enough not
0094 to add extra (unwanted) `<p>` tags around HTML block-level tags.
0095 
0096 For example, to add an HTML table to a Markdown article:
0097 
0098     This is a regular paragraph.
0099 
0100     <table>
0101         <tr>
0102             <td>Foo</td>
0103         </tr>
0104     </table>
0105 
0106     This is another regular paragraph.
0107 
0108 Note that Markdown formatting syntax is not processed within block-level
0109 HTML tags. E.g., you can't use Markdown-style `*emphasis*` inside an
0110 HTML block.
0111 
0112 Span-level HTML tags -- e.g. `<span>`, `<cite>`, or `<del>` -- can be
0113 used anywhere in a Markdown paragraph, list item, or header. If you
0114 want, you can even use HTML tags instead of Markdown formatting; e.g. if
0115 you'd prefer to use HTML `<a>` or `<img>` tags instead of Markdown's
0116 link or image syntax, go right ahead.
0117 
0118 Unlike block-level HTML tags, Markdown syntax *is* processed within
0119 span-level tags.
0120 
0121 
0122 <h3 id="autoescape">Automatic Escaping for Special Characters</h3>
0123 
0124 In HTML, there are two characters that demand special treatment: `<`
0125 and `&`. Left angle brackets are used to start tags; ampersands are
0126 used to denote HTML entities. If you want to use them as literal
0127 characters, you must escape them as entities, e.g. `&lt;`, and
0128 `&amp;`.
0129 
0130 Ampersands in particular are bedeviling for web writers. If you want to
0131 write about 'AT&T', you need to write '`AT&amp;T`'. You even need to
0132 escape ampersands within URLs. Thus, if you want to link to:
0133 
0134     http://images.google.com/images?num=30&q=larry+bird
0135 
0136 you need to encode the URL as:
0137 
0138     http://images.google.com/images?num=30&amp;q=larry+bird
0139 
0140 in your anchor tag `href` attribute. Needless to say, this is easy to
0141 forget, and is probably the single most common source of HTML validation
0142 errors in otherwise well-marked-up web sites.
0143 
0144 Markdown allows you to use these characters naturally, taking care of
0145 all the necessary escaping for you. If you use an ampersand as part of
0146 an HTML entity, it remains unchanged; otherwise it will be translated
0147 into `&amp;`.
0148 
0149 So, if you want to include a copyright symbol in your article, you can write:
0150 
0151     &copy;
0152 
0153 and Markdown will leave it alone. But if you write:
0154 
0155     AT&T
0156 
0157 Markdown will translate it to:
0158 
0159     AT&amp;T
0160 
0161 Similarly, because Markdown supports [inline HTML](#html), if you use
0162 angle brackets as delimiters for HTML tags, Markdown will treat them as
0163 such. But if you write:
0164 
0165     4 < 5
0166 
0167 Markdown will translate it to:
0168 
0169     4 &lt; 5
0170 
0171 However, inside Markdown code spans and blocks, angle brackets and
0172 ampersands are *always* encoded automatically. This makes it easy to use
0173 Markdown to write about HTML code. (As opposed to raw HTML, which is a
0174 terrible format for writing about HTML syntax, because every single `<`
0175 and `&` in your example code needs to be escaped.)
0176 
0177 
0178 * * *
0179 
0180 
0181 <h2 id="block">Block Elements</h2>
0182 
0183 
0184 <h3 id="p">Paragraphs and Line Breaks</h3>
0185 
0186 A paragraph is simply one or more consecutive lines of text, separated
0187 by one or more blank lines. (A blank line is any line that looks like a
0188 blank line -- a line containing nothing but spaces or tabs is considered
0189 blank.) Normal paragraphs should not be indented with spaces or tabs.
0190 
0191 The implication of the "one or more consecutive lines of text" rule is
0192 that Markdown supports "hard-wrapped" text paragraphs. This differs
0193 significantly from most other text-to-HTML formatters (including Movable
0194 Type's "Convert Line Breaks" option) which translate every line break
0195 character in a paragraph into a `<br />` tag.
0196 
0197 When you *do* want to insert a `<br />` break tag using Markdown, you
0198 end a line with two or more spaces, then type return.
0199 
0200 Yes, this takes a tad more effort to create a `<br />`, but a simplistic
0201 "every line break is a `<br />`" rule wouldn't work for Markdown.
0202 Markdown's email-style [blockquoting][bq] and multi-paragraph [list items][l]
0203 work best -- and look better -- when you format them with hard breaks.
0204 
0205   [bq]: #blockquote
0206   [l]:  #list
0207 
0208 
0209 
0210 <h3 id="header">Headers</h3>
0211 
0212 Markdown supports two styles of headers, [Setext] [1] and [atx] [2].
0213 
0214 Setext-style headers are "underlined" using equal signs (for first-level
0215 headers) and dashes (for second-level headers). For example:
0216 
0217     This is an H1
0218     =============
0219 
0220     This is an H2
0221     -------------
0222 
0223 Any number of underlining `=`'s or `-`'s will work.
0224 
0225 Atx-style headers use 1-6 hash characters at the start of the line,
0226 corresponding to header levels 1-6. For example:
0227 
0228     # This is an H1
0229 
0230     ## This is an H2
0231 
0232     ###### This is an H6
0233 
0234 Optionally, you may "close" atx-style headers. This is purely
0235 cosmetic -- you can use this if you think it looks better. The
0236 closing hashes don't even need to match the number of hashes
0237 used to open the header. (The number of opening hashes
0238 determines the header level.) :
0239 
0240     # This is an H1 #
0241 
0242     ## This is an H2 ##
0243 
0244     ### This is an H3 ######
0245 
0246 
0247 <h3 id="blockquote">Blockquotes</h3>
0248 
0249 Markdown uses email-style `>` characters for blockquoting. If you're
0250 familiar with quoting passages of text in an email message, then you
0251 know how to create a blockquote in Markdown. It looks best if you hard
0252 wrap the text and put a `>` before every line:
0253 
0254     > This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
0255     > consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
0256     > Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
0257     > 
0258     > Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
0259     > id sem consectetuer libero luctus adipiscing.
0260 
0261 Markdown allows you to be lazy and only put the `>` before the first
0262 line of a hard-wrapped paragraph:
0263 
0264     > This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
0265     consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
0266     Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
0267 
0268     > Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
0269     id sem consectetuer libero luctus adipiscing.
0270 
0271 Blockquotes can be nested (i.e. a blockquote-in-a-blockquote) by
0272 adding additional levels of `>`:
0273 
0274     > This is the first level of quoting.
0275     >
0276     > > This is nested blockquote.
0277     >
0278     > Back to the first level.
0279 
0280 Blockquotes can contain other Markdown elements, including headers, lists,
0281 and code blocks:
0282 
0283         > ## This is a header.
0284         > 
0285         > 1.   This is the first list item.
0286         > 2.   This is the second list item.
0287         > 
0288         > Here's some example code:
0289         > 
0290         >     return shell_exec("echo $input | $markdown_script");
0291 
0292 Any decent text editor should make email-style quoting easy. For
0293 example, with BBEdit, you can make a selection and choose Increase
0294 Quote Level from the Text menu.
0295 
0296 
0297 <h3 id="list">Lists</h3>
0298 
0299 Markdown supports ordered (numbered) and unordered (bulleted) lists.
0300 
0301 Unordered lists use asterisks, pluses, and hyphens -- interchangably
0302 -- as list markers:
0303 
0304     *   Red
0305     *   Green
0306     *   Blue
0307 
0308 is equivalent to:
0309 
0310     +   Red
0311     +   Green
0312     +   Blue
0313 
0314 and:
0315 
0316     -   Red
0317     -   Green
0318     -   Blue
0319 
0320 Ordered lists use numbers followed by periods:
0321 
0322     1.  Bird
0323     2.  McHale
0324     3.  Parish
0325 
0326 It's important to note that the actual numbers you use to mark the
0327 list have no effect on the HTML output Markdown produces. The HTML
0328 Markdown produces from the above list is:
0329 
0330     <ol>
0331     <li>Bird</li>
0332     <li>McHale</li>
0333     <li>Parish</li>
0334     </ol>
0335 
0336 If you instead wrote the list in Markdown like this:
0337 
0338     1.  Bird
0339     1.  McHale
0340     1.  Parish
0341 
0342 or even:
0343 
0344     3. Bird
0345     1. McHale
0346     8. Parish
0347 
0348 you'd get the exact same HTML output. The point is, if you want to,
0349 you can use ordinal numbers in your ordered Markdown lists, so that
0350 the numbers in your source match the numbers in your published HTML.
0351 But if you want to be lazy, you don't have to.
0352 
0353 If you do use lazy list numbering, however, you should still start the
0354 list with the number 1. At some point in the future, Markdown may support
0355 starting ordered lists at an arbitrary number.
0356 
0357 List markers typically start at the left margin, but may be indented by
0358 up to three spaces. List markers must be followed by one or more spaces
0359 or a tab.
0360 
0361 To make lists look nice, you can wrap items with hanging indents:
0362 
0363     *   Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
0364         Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
0365         viverra nec, fringilla in, laoreet vitae, risus.
0366     *   Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
0367         Suspendisse id sem consectetuer libero luctus adipiscing.
0368 
0369 But if you want to be lazy, you don't have to:
0370 
0371     *   Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
0372     Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
0373     viverra nec, fringilla in, laoreet vitae, risus.
0374     *   Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
0375     Suspendisse id sem consectetuer libero luctus adipiscing.
0376 
0377 If list items are separated by blank lines, Markdown will wrap the
0378 items in `<p>` tags in the HTML output. For example, this input:
0379 
0380     *   Bird
0381     *   Magic
0382 
0383 will turn into:
0384 
0385     <ul>
0386     <li>Bird</li>
0387     <li>Magic</li>
0388     </ul>
0389 
0390 But this:
0391 
0392     *   Bird
0393 
0394     *   Magic
0395 
0396 will turn into:
0397 
0398     <ul>
0399     <li><p>Bird</p></li>
0400     <li><p>Magic</p></li>
0401     </ul>
0402 
0403 List items may consist of multiple paragraphs. Each subsequent
0404 paragraph in a list item must be intended by either 4 spaces
0405 or one tab:
0406 
0407     1.  This is a list item with two paragraphs. Lorem ipsum dolor
0408         sit amet, consectetuer adipiscing elit. Aliquam hendrerit
0409         mi posuere lectus.
0410 
0411         Vestibulum enim wisi, viverra nec, fringilla in, laoreet
0412         vitae, risus. Donec sit amet nisl. Aliquam semper ipsum
0413         sit amet velit.
0414 
0415     2.  Suspendisse id sem consectetuer libero luctus adipiscing.
0416 
0417 It looks nice if you indent every line of the subsequent
0418 paragraphs, but here again, Markdown will allow you to be
0419 lazy:
0420 
0421     *   This is a list item with two paragraphs.
0422 
0423         This is the second paragraph in the list item. You're
0424     only required to indent the first line. Lorem ipsum dolor
0425     sit amet, consectetuer adipiscing elit.
0426 
0427     *   Another item in the same list.
0428 
0429 To put a blockquote within a list item, the blockquote's `>`
0430 delimiters need to be indented:
0431 
0432     *   A list item with a blockquote:
0433 
0434         > This is a blockquote
0435         > inside a list item.
0436 
0437 To put a code block within a list item, the code block needs
0438 to be indented *twice* -- 8 spaces or two tabs:
0439 
0440     *   A list item with a code block:
0441 
0442             <code goes here>
0443 
0444 
0445 It's worth noting that it's possible to trigger an ordered list by
0446 accident, by writing something like this:
0447 
0448     1986. What a great season.
0449 
0450 In other words, a *number-period-space* sequence at the beginning of a
0451 line. To avoid this, you can backslash-escape the period:
0452 
0453     1986\. What a great season.
0454 
0455 
0456 
0457 <h3 id="precode">Code Blocks</h3>
0458 
0459 Pre-formatted code blocks are used for writing about programming or
0460 markup source code. Rather than forming normal paragraphs, the lines
0461 of a code block are interpreted literally. Markdown wraps a code block
0462 in both `<pre>` and `<code>` tags.
0463 
0464 To produce a code block in Markdown, simply indent every line of the
0465 block by at least 4 spaces or 1 tab. For example, given this input:
0466 
0467     This is a normal paragraph:
0468 
0469         This is a code block.
0470 
0471 Markdown will generate:
0472 
0473     <p>This is a normal paragraph:</p>
0474 
0475     <pre><code>This is a code block.
0476     </code></pre>
0477 
0478 One level of indentation -- 4 spaces or 1 tab -- is removed from each
0479 line of the code block. For example, this:
0480 
0481     Here is an example of AppleScript:
0482 
0483         tell application "Foo"
0484             beep
0485         end tell
0486 
0487 will turn into:
0488 
0489     <p>Here is an example of AppleScript:</p>
0490 
0491     <pre><code>tell application "Foo"
0492         beep
0493     end tell
0494     </code></pre>
0495 
0496 A code block continues until it reaches a line that is not indented
0497 (or the end of the article).
0498 
0499 Within a code block, ampersands (`&`) and angle brackets (`<` and `>`)
0500 are automatically converted into HTML entities. This makes it very
0501 easy to include example HTML source code using Markdown -- just paste
0502 it and indent it, and Markdown will handle the hassle of encoding the
0503 ampersands and angle brackets. For example, this:
0504 
0505         <div class="footer">
0506             &copy; 2004 Foo Corporation
0507         </div>
0508 
0509 will turn into:
0510 
0511     <pre><code>&lt;div class="footer"&gt;
0512         &amp;copy; 2004 Foo Corporation
0513     &lt;/div&gt;
0514     </code></pre>
0515 
0516 Regular Markdown syntax is not processed within code blocks. E.g.,
0517 asterisks are just literal asterisks within a code block. This means
0518 it's also easy to use Markdown to write about Markdown's own syntax.
0519 
0520 
0521 
0522 <h3 id="hr">Horizontal Rules</h3>
0523 
0524 You can produce a horizontal rule tag (`<hr />`) by placing three or
0525 more hyphens, asterisks, or underscores on a line by themselves. If you
0526 wish, you may use spaces between the hyphens or asterisks. Each of the
0527 following lines will produce a horizontal rule:
0528 
0529     * * *
0530 
0531     ***
0532 
0533     *****
0534 
0535     - - -
0536 
0537     ---------------------------------------
0538 
0539 
0540 * * *
0541 
0542 <h2 id="span">Span Elements</h2>
0543 
0544 <h3 id="link">Links</h3>
0545 
0546 Markdown supports two style of links: *inline* and *reference*.
0547 
0548 In both styles, the link text is delimited by [square brackets].
0549 
0550 To create an inline link, use a set of regular parentheses immediately
0551 after the link text's closing square bracket. Inside the parentheses,
0552 put the URL where you want the link to point, along with an *optional*
0553 title for the link, surrounded in quotes. For example:
0554 
0555     This is [an example](http://example.com/ "Title") inline link.
0556 
0557     [This link](http://example.net/) has no title attribute.
0558 
0559 Will produce:
0560 
0561     <p>This is <a href="http://example.com/" title="Title">
0562     an example</a> inline link.</p>
0563 
0564     <p><a href="http://example.net/">This link</a> has no
0565     title attribute.</p>
0566 
0567 If you're referring to a local resource on the same server, you can
0568 use relative paths:
0569 
0570     See my [About](/about/) page for details.   
0571 
0572 Reference-style links use a second set of square brackets, inside
0573 which you place a label of your choosing to identify the link:
0574 
0575     This is [an example][id] reference-style link.
0576 
0577 You can optionally use a space to separate the sets of brackets:
0578 
0579     This is [an example] [id] reference-style link.
0580 
0581 Then, anywhere in the document, you define your link label like this,
0582 on a line by itself:
0583 
0584     [id]: http://example.com/  "Optional Title Here"
0585 
0586 That is:
0587 
0588 *   Square brackets containing the link identifier (optionally
0589     indented from the left margin using up to three spaces);
0590 *   followed by a colon;
0591 *   followed by one or more spaces (or tabs);
0592 *   followed by the URL for the link;
0593 *   optionally followed by a title attribute for the link, enclosed
0594     in double or single quotes, or enclosed in parentheses.
0595 
0596 The following three link definitions are equivalent:
0597 
0598         [foo]: http://example.com/  "Optional Title Here"
0599         [foo]: http://example.com/  'Optional Title Here'
0600         [foo]: http://example.com/  (Optional Title Here)
0601 
0602 **Note:** There is a known bug in Markdown.pl 1.0.1 which prevents
0603 single quotes from being used to delimit link titles.
0604 
0605 The link URL may, optionally, be surrounded by angle brackets:
0606 
0607     [id]: <http://example.com/>  "Optional Title Here"
0608 
0609 You can put the title attribute on the next line and use extra spaces
0610 or tabs for padding, which tends to look better with longer URLs:
0611 
0612     [id]: http://example.com/longish/path/to/resource/here
0613         "Optional Title Here"
0614 
0615 Link definitions are only used for creating links during Markdown
0616 processing, and are stripped from your document in the HTML output.
0617 
0618 Link definition names may constist of letters, numbers, spaces, and
0619 punctuation -- but they are *not* case sensitive. E.g. these two
0620 links:
0621 
0622         [link text][a]
0623         [link text][A]
0624 
0625 are equivalent.
0626 
0627 The *implicit link name* shortcut allows you to omit the name of the
0628 link, in which case the link text itself is used as the name.
0629 Just use an empty set of square brackets -- e.g., to link the word
0630 "Google" to the google.com web site, you could simply write:
0631 
0632         [Google][]
0633 
0634 And then define the link:
0635 
0636         [Google]: http://google.com/
0637 
0638 Because link names may contain spaces, this shortcut even works for
0639 multiple words in the link text:
0640 
0641         Visit [Daring Fireball][] for more information.
0642 
0643 And then define the link:
0644         
0645         [Daring Fireball]: http://daringfireball.net/
0646 
0647 Link definitions can be placed anywhere in your Markdown document. I
0648 tend to put them immediately after each paragraph in which they're
0649 used, but if you want, you can put them all at the end of your
0650 document, sort of like footnotes.
0651 
0652 Here's an example of reference links in action:
0653 
0654     I get 10 times more traffic from [Google] [1] than from
0655     [Yahoo] [2] or [MSN] [3].
0656 
0657       [1]: http://google.com/        "Google"
0658       [2]: http://search.yahoo.com/  "Yahoo Search"
0659       [3]: http://search.msn.com/    "MSN Search"
0660 
0661 Using the implicit link name shortcut, you could instead write:
0662 
0663     I get 10 times more traffic from [Google][] than from
0664     [Yahoo][] or [MSN][].
0665 
0666       [google]: http://google.com/        "Google"
0667       [yahoo]:  http://search.yahoo.com/  "Yahoo Search"
0668       [msn]:    http://search.msn.com/    "MSN Search"
0669 
0670 Both of the above examples will produce the following HTML output:
0671 
0672     <p>I get 10 times more traffic from <a href="http://google.com/"
0673     title="Google">Google</a> than from
0674     <a href="http://search.yahoo.com/" title="Yahoo Search">Yahoo</a>
0675     or <a href="http://search.msn.com/" title="MSN Search">MSN</a>.</p>
0676 
0677 For comparison, here is the same paragraph written using
0678 Markdown's inline link style:
0679 
0680     I get 10 times more traffic from [Google](http://google.com/ "Google")
0681     than from [Yahoo](http://search.yahoo.com/ "Yahoo Search") or
0682     [MSN](http://search.msn.com/ "MSN Search").
0683 
0684 The point of reference-style links is not that they're easier to
0685 write. The point is that with reference-style links, your document
0686 source is vastly more readable. Compare the above examples: using
0687 reference-style links, the paragraph itself is only 81 characters
0688 long; with inline-style links, it's 176 characters; and as raw HTML,
0689 it's 234 characters. In the raw HTML, there's more markup than there
0690 is text.
0691 
0692 With Markdown's reference-style links, a source document much more
0693 closely resembles the final output, as rendered in a browser. By
0694 allowing you to move the markup-related metadata out of the paragraph,
0695 you can add links without interrupting the narrative flow of your
0696 prose.
0697 
0698 
0699 <h3 id="em">Emphasis</h3>
0700 
0701 Markdown treats asterisks (`*`) and underscores (`_`) as indicators of
0702 emphasis. Text wrapped with one `*` or `_` will be wrapped with an
0703 HTML `<em>` tag; double `*`'s or `_`'s will be wrapped with an HTML
0704 `<strong>` tag. E.g., this input:
0705 
0706     *single asterisks*
0707 
0708     _single underscores_
0709 
0710     **double asterisks**
0711 
0712     __double underscores__
0713 
0714 will produce:
0715 
0716     <em>single asterisks</em>
0717 
0718     <em>single underscores</em>
0719 
0720     <strong>double asterisks</strong>
0721 
0722     <strong>double underscores</strong>
0723 
0724 You can use whichever style you prefer; the lone restriction is that
0725 the same character must be used to open and close an emphasis span.
0726 
0727 Emphasis can be used in the middle of a word:
0728 
0729     un*fucking*believable
0730 
0731 But if you surround an `*` or `_` with spaces, it'll be treated as a
0732 literal asterisk or underscore.
0733 
0734 To produce a literal asterisk or underscore at a position where it
0735 would otherwise be used as an emphasis delimiter, you can backslash
0736 escape it:
0737 
0738     \*this text is surrounded by literal asterisks\*
0739 
0740 
0741 
0742 <h3 id="code">Code</h3>
0743 
0744 To indicate a span of code, wrap it with backtick quotes (`` ` ``).
0745 Unlike a pre-formatted code block, a code span indicates code within a
0746 normal paragraph. For example:
0747 
0748     Use the `printf()` function.
0749 
0750 will produce:
0751 
0752     <p>Use the <code>printf()</code> function.</p>
0753 
0754 To include a literal backtick character within a code span, you can use
0755 multiple backticks as the opening and closing delimiters:
0756 
0757     ``There is a literal backtick (`) here.``
0758 
0759 which will produce this:
0760 
0761     <p><code>There is a literal backtick (`) here.</code></p>
0762 
0763 The backtick delimiters surrounding a code span may include spaces --
0764 one after the opening, one before the closing. This allows you to place
0765 literal backtick characters at the beginning or end of a code span:
0766 
0767         A single backtick in a code span: `` ` ``
0768         
0769         A backtick-delimited string in a code span: `` `foo` ``
0770 
0771 will produce:
0772 
0773         <p>A single backtick in a code span: <code>`</code></p>
0774         
0775         <p>A backtick-delimited string in a code span: <code>`foo`</code></p>
0776 
0777 With a code span, ampersands and angle brackets are encoded as HTML
0778 entities automatically, which makes it easy to include example HTML
0779 tags. Markdown will turn this:
0780 
0781     Please don't use any `<blink>` tags.
0782 
0783 into:
0784 
0785     <p>Please don't use any <code>&lt;blink&gt;</code> tags.</p>
0786 
0787 You can write this:
0788 
0789     `&#8212;` is the decimal-encoded equivalent of `&mdash;`.
0790 
0791 to produce:
0792 
0793     <p><code>&amp;#8212;</code> is the decimal-encoded
0794     equivalent of <code>&amp;mdash;</code>.</p>
0795 
0796 
0797 
0798 <h3 id="img">Images</h3>
0799 
0800 Admittedly, it's fairly difficult to devise a "natural" syntax for
0801 placing images into a plain text document format.
0802 
0803 Markdown uses an image syntax that is intended to resemble the syntax
0804 for links, allowing for two styles: *inline* and *reference*.
0805 
0806 Inline image syntax looks like this:
0807 
0808     ![Alt text](/path/to/img.jpg)
0809 
0810     ![Alt text](/path/to/img.jpg "Optional title")
0811 
0812 That is:
0813 
0814 *   An exclamation mark: `!`;
0815 *   followed by a set of square brackets, containing the `alt`
0816     attribute text for the image;
0817 *   followed by a set of parentheses, containing the URL or path to
0818     the image, and an optional `title` attribute enclosed in double
0819     or single quotes.
0820 
0821 Reference-style image syntax looks like this:
0822 
0823     ![Alt text][id]
0824 
0825 Where "id" is the name of a defined image reference. Image references
0826 are defined using syntax identical to link references:
0827 
0828     [id]: url/to/image  "Optional title attribute"
0829 
0830 As of this writing, Markdown has no syntax for specifying the
0831 dimensions of an image; if this is important to you, you can simply
0832 use regular HTML `<img>` tags.
0833 
0834 
0835 * * *
0836 
0837 
0838 <h2 id="misc">Miscellaneous</h2>
0839 
0840 <h3 id="autolink">Automatic Links</h3>
0841 
0842 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:
0843 
0844     <http://example.com/>
0845     
0846 Markdown will turn this into:
0847 
0848     <a href="http://example.com/">http://example.com/</a>
0849 
0850 Automatic links for email addresses work similarly, except that
0851 Markdown will also perform a bit of randomized decimal and hex
0852 entity-encoding to help obscure your address from address-harvesting
0853 spambots. For example, Markdown will turn this:
0854 
0855     <address@example.com>
0856 
0857 into something like this:
0858 
0859     <a href="&#x6D;&#x61;i&#x6C;&#x74;&#x6F;:&#x61;&#x64;&#x64;&#x72;&#x65;
0860     &#115;&#115;&#64;&#101;&#120;&#x61;&#109;&#x70;&#x6C;e&#x2E;&#99;&#111;
0861     &#109;">&#x61;&#x64;&#x64;&#x72;&#x65;&#115;&#115;&#64;&#101;&#120;&#x61;
0862     &#109;&#x70;&#x6C;e&#x2E;&#99;&#111;&#109;</a>
0863 
0864 which will render in a browser as a clickable link to "address@example.com".
0865 
0866 (This sort of entity-encoding trick will indeed fool many, if not
0867 most, address-harvesting bots, but it definitely won't fool all of
0868 them. It's better than nothing, but an address published in this way
0869 will probably eventually start receiving spam.)
0870 
0871 
0872 
0873 <h3 id="backslash">Backslash Escapes</h3>
0874 
0875 Markdown allows you to use backslash escapes to generate literal
0876 characters which would otherwise have special meaning in Markdown's
0877 formatting syntax. For example, if you wanted to surround a word with
0878 literal asterisks (instead of an HTML `<em>` tag), you can backslashes
0879 before the asterisks, like this:
0880 
0881     \*literal asterisks\*
0882 
0883 Markdown provides backslash escapes for the following characters:
0884 
0885     \   backslash
0886     `   backtick
0887     *   asterisk
0888     _   underscore
0889     {}  curly braces
0890     []  square brackets
0891     ()  parentheses
0892     #   hash mark
0893         +       plus sign
0894         -       minus sign (hyphen)
0895     .   dot
0896     !   exclamation mark
0897