4 caption: [ Ken Grimes, Mad Computer Scientist At Large ]
7 This is a website I've constructed for the purpose of developing blogging
8 software. I will probably blog with it once development is complete. In the mean
9 time, if you're curious, this is my [curriculum vitae](cv.pdf).
14 <ul id="ProjectSubmenu">
15 <li><a href="/projects/markdown/" title="Markdown Project Page">Main</a></li>
16 <li><a href="/projects/markdown/basics" title="Markdown Basics">Basics</a></li>
17 <li><a class="selected" title="Markdown Syntax Documentation">Syntax</a></li>
18 <li><a href="/projects/markdown/license" title="Pricing and License Information">License</a></li>
19 <li><a href="/projects/markdown/dingus" title="Online Markdown Web Form">Dingus</a></li>
23 * [Overview](#overview)
24 * [Philosophy](#philosophy)
25 * [Inline HTML](#html)
26 * [Automatic Escaping for Special Characters](#autoescape)
27 * [Block Elements](#block)
28 * [Paragraphs and Line Breaks](#p)
30 * [Blockquotes](#blockquote)
32 * [Code Blocks](#precode)
33 * [Horizontal Rules](#hr)
34 * [Span Elements](#span)
39 * [Miscellaneous](#misc)
40 * [Backslash Escapes](#backslash)
41 * [Automatic Links](#autolink)
44 **Note:** This document is itself written using Markdown; you
45 can [see the source for it by adding '.text' to the URL][src].
47 [src]: /projects/markdown/syntax.text
51 <h2 id="overview">Overview</h2>
53 <h3 id="philosophy">Philosophy</h3>
55 Markdown is intended to be as easy-to-read and easy-to-write as is feasible.
57 Readability, however, is emphasized above all else. A Markdown-formatted
58 document should be publishable as-is, as plain text, without looking
59 like it's been marked up with tags or formatting instructions. While
60 Markdown's syntax has been influenced by several existing text-to-HTML
61 filters -- including [Setext] [1], [atx] [2], [Textile] [3], [reStructuredText] [4],
62 [Grutatext] [5], and [EtText] [6] -- the single biggest source of
63 inspiration for Markdown's syntax is the format of plain text email.
65 [1]: http://docutils.sourceforge.net/mirror/setext.html
66 [2]: http://www.aaronsw.com/2002/atx/
67 [3]: http://textism.com/tools/textile/
68 [4]: http://docutils.sourceforge.net/rst.html
69 [5]: http://www.triptico.com/software/grutatxt.html
70 [6]: http://ettext.taint.org/doc/
72 To this end, Markdown's syntax is comprised entirely of punctuation
73 characters, which punctuation characters have been carefully chosen so
74 as to look like what they mean. E.g., asterisks around a word actually
75 look like \*emphasis\*. Markdown lists look like, well, lists. Even
76 blockquotes look like quoted passages of text, assuming you've ever
81 <h3 id="html">Inline HTML</h3>
83 Markdown's syntax is intended for one purpose: to be used as a
84 format for *writing* for the web.
86 Markdown is not a replacement for HTML, or even close to it. Its
87 syntax is very small, corresponding only to a very small subset of
88 HTML tags. The idea is *not* to create a syntax that makes it easier
89 to insert HTML tags. In my opinion, HTML tags are already easy to
90 insert. The idea for Markdown is to make it easy to read, write, and
91 edit prose. HTML is a *publishing* format; Markdown is a *writing*
92 format. Thus, Markdown's formatting syntax only addresses issues that
93 can be conveyed in plain text.
95 For any markup that is not covered by Markdown's syntax, you simply
96 use HTML itself. There's no need to preface it or delimit it to
97 indicate that you're switching from Markdown to HTML; you just use
100 The only restrictions are that block-level HTML elements -- e.g. `<div>`,
101 `<table>`, `<pre>`, `<p>`, etc. -- must be separated from surrounding
102 content by blank lines, and the start and end tags of the block should
103 not be indented with tabs or spaces. Markdown is smart enough not
104 to add extra (unwanted) `<p>` tags around HTML block-level tags.
106 For example, to add an HTML table to a Markdown article:
108 This is a regular paragraph.
116 This is another regular paragraph.
118 Note that Markdown formatting syntax is not processed within block-level
119 HTML tags. E.g., you can't use Markdown-style `*emphasis*` inside an
122 Span-level HTML tags -- e.g. `<span>`, `<cite>`, or `<del>` -- can be
123 used anywhere in a Markdown paragraph, list item, or header. If you
124 want, you can even use HTML tags instead of Markdown formatting; e.g. if
125 you'd prefer to use HTML `<a>` or `<img>` tags instead of Markdown's
126 link or image syntax, go right ahead.
128 Unlike block-level HTML tags, Markdown syntax *is* processed within
132 <h3 id="autoescape">Automatic Escaping for Special Characters</h3>
134 In HTML, there are two characters that demand special treatment: `<`
135 and `&`. Left angle brackets are used to start tags; ampersands are
136 used to denote HTML entities. If you want to use them as literal
137 characters, you must escape them as entities, e.g. `<`, and
140 Ampersands in particular are bedeviling for web writers. If you want to
141 write about 'AT&T', you need to write '`AT&T`'. You even need to
142 escape ampersands within URLs. Thus, if you want to link to:
144 http://images.google.com/images?num=30&q=larry+bird
146 you need to encode the URL as:
148 http://images.google.com/images?num=30&q=larry+bird
150 in your anchor tag `href` attribute. Needless to say, this is easy to
151 forget, and is probably the single most common source of HTML validation
152 errors in otherwise well-marked-up web sites.
154 Markdown allows you to use these characters naturally, taking care of
155 all the necessary escaping for you. If you use an ampersand as part of
156 an HTML entity, it remains unchanged; otherwise it will be translated
159 So, if you want to include a copyright symbol in your article, you can write:
163 and Markdown will leave it alone. But if you write:
167 Markdown will translate it to:
171 Similarly, because Markdown supports [inline HTML](#html), if you use
172 angle brackets as delimiters for HTML tags, Markdown will treat them as
173 such. But if you write:
177 Markdown will translate it to:
181 However, inside Markdown code spans and blocks, angle brackets and
182 ampersands are *always* encoded automatically. This makes it easy to use
183 Markdown to write about HTML code. (As opposed to raw HTML, which is a
184 terrible format for writing about HTML syntax, because every single `<`
185 and `&` in your example code needs to be escaped.)
191 <h2 id="block">Block Elements</h2>
194 <h3 id="p">Paragraphs and Line Breaks</h3>
196 A paragraph is simply one or more consecutive lines of text, separated
197 by one or more blank lines. (A blank line is any line that looks like a
198 blank line -- a line containing nothing but spaces or tabs is considered
199 blank.) Normal paragraphs should not be intended with spaces or tabs.
201 The implication of the "one or more consecutive lines of text" rule is
202 that Markdown supports "hard-wrapped" text paragraphs. This differs
203 significantly from most other text-to-HTML formatters (including Movable
204 Type's "Convert Line Breaks" option) which translate every line break
205 character in a paragraph into a `<br />` tag.
207 When you *do* want to insert a `<br />` break tag using Markdown, you
208 end a line with two or more spaces, then type return.
210 Yes, this takes a tad more effort to create a `<br />`, but a simplistic
211 "every line break is a `<br />`" rule wouldn't work for Markdown.
212 Markdown's email-style [blockquoting][bq] and multi-paragraph [list items][l]
213 work best -- and look better -- when you format them with hard breaks.
220 <h3 id="header">Headers</h3>
222 Markdown supports two styles of headers, [Setext] [1] and [atx] [2].
224 Setext-style headers are "underlined" using equal signs (for first-level
225 headers) and dashes (for second-level headers). For example:
233 Any number of underlining `=`'s or `-`'s will work.
235 Atx-style headers use 1-6 hash characters at the start of the line,
236 corresponding to header levels 1-6. For example:
244 Optionally, you may "close" atx-style headers. This is purely
245 cosmetic -- you can use this if you think it looks better. The
246 closing hashes don't even need to match the number of hashes
247 used to open the header. (The number of opening hashes
248 determines the header level.) :
254 ### This is an H3 ######
257 <h3 id="blockquote">Blockquotes</h3>
259 Markdown uses email-style `>` characters for blockquoting. If you're
260 familiar with quoting passages of text in an email message, then you
261 know how to create a blockquote in Markdown. It looks best if you hard
262 wrap the text and put a `>` before every line:
264 > This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
265 > consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
266 > Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
268 > Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
269 > id sem consectetuer libero luctus adipiscing.
271 Markdown allows you to be lazy and only put the `>` before the first
272 line of a hard-wrapped paragraph:
274 > This is a blockquote with two paragraphs. Lorem ipsum dolor sit amet,
275 consectetuer adipiscing elit. Aliquam hendrerit mi posuere lectus.
276 Vestibulum enim wisi, viverra nec, fringilla in, laoreet vitae, risus.
278 > Donec sit amet nisl. Aliquam semper ipsum sit amet velit. Suspendisse
279 id sem consectetuer libero luctus adipiscing.
281 Blockquotes can be nested (i.e. a blockquote-in-a-blockquote) by
282 adding additional levels of `>`:
284 > This is the first level of quoting.
286 > > This is nested blockquote.
288 > Back to the first level.
290 Blockquotes can contain other Markdown elements, including headers, lists,
293 > ## This is a header.
295 > 1. This is the first list item.
296 > 2. This is the second list item.
298 > Here's some example code:
300 > return shell_exec("echo $input | $markdown_script");
302 Any decent text editor should make email-style quoting easy. For
303 example, with BBEdit, you can make a selection and choose Increase
304 Quote Level from the Text menu.
307 <h3 id="list">Lists</h3>
309 Markdown supports ordered (numbered) and unordered (bulleted) lists.
311 Unordered lists use asterisks, pluses, and hyphens -- interchangably
330 Ordered lists use numbers followed by periods:
336 It's important to note that the actual numbers you use to mark the
337 list have no effect on the HTML output Markdown produces. The HTML
338 Markdown produces from the above list is:
346 If you instead wrote the list in Markdown like this:
358 you'd get the exact same HTML output. The point is, if you want to,
359 you can use ordinal numbers in your ordered Markdown lists, so that
360 the numbers in your source match the numbers in your published HTML.
361 But if you want to be lazy, you don't have to.
363 If you do use lazy list numbering, however, you should still start the
364 list with the number 1. At some point in the future, Markdown may support
365 starting ordered lists at an arbitrary number.
367 List markers typically start at the left margin, but may be indented by
368 up to three spaces. List markers must be followed by one or more spaces
371 To make lists look nice, you can wrap items with hanging indents:
373 * Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
374 Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
375 viverra nec, fringilla in, laoreet vitae, risus.
376 * Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
377 Suspendisse id sem consectetuer libero luctus adipiscing.
379 But if you want to be lazy, you don't have to:
381 * Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
382 Aliquam hendrerit mi posuere lectus. Vestibulum enim wisi,
383 viverra nec, fringilla in, laoreet vitae, risus.
384 * Donec sit amet nisl. Aliquam semper ipsum sit amet velit.
385 Suspendisse id sem consectetuer libero luctus adipiscing.
387 If list items are separated by blank lines, Markdown will wrap the
388 items in `<p>` tags in the HTML output. For example, this input:
410 <li><p>Magic</p></li>
413 List items may consist of multiple paragraphs. Each subsequent
414 paragraph in a list item must be intended by either 4 spaces
417 1. This is a list item with two paragraphs. Lorem ipsum dolor
418 sit amet, consectetuer adipiscing elit. Aliquam hendrerit
421 Vestibulum enim wisi, viverra nec, fringilla in, laoreet
422 vitae, risus. Donec sit amet nisl. Aliquam semper ipsum
425 2. Suspendisse id sem consectetuer libero luctus adipiscing.
427 It looks nice if you indent every line of the subsequent
428 paragraphs, but here again, Markdown will allow you to be
431 * This is a list item with two paragraphs.
433 This is the second paragraph in the list item. You're
434 only required to indent the first line. Lorem ipsum dolor
435 sit amet, consectetuer adipiscing elit.
437 * Another item in the same list.
439 To put a blockquote within a list item, the blockquote's `>`
440 delimiters need to be indented:
442 * A list item with a blockquote:
444 > This is a blockquote
445 > inside a list item.
447 To put a code block within a list item, the code block needs
448 to be indented *twice* -- 8 spaces or two tabs:
450 * A list item with a code block:
455 It's worth noting that it's possible to trigger an ordered list by
456 accident, by writing something like this:
458 1986. What a great season.
460 In other words, a *number-period-space* sequence at the beginning of a
461 line. To avoid this, you can backslash-escape the period:
463 1986\. What a great season.
467 <h3 id="precode">Code Blocks</h3>
469 Pre-formatted code blocks are used for writing about programming or
470 markup source code. Rather than forming normal paragraphs, the lines
471 of a code block are interpreted literally. Markdown wraps a code block
472 in both `<pre>` and `<code>` tags.
474 To produce a code block in Markdown, simply indent every line of the
475 block by at least 4 spaces or 1 tab. For example, given this input:
477 This is a normal paragraph:
479 This is a code block.
481 Markdown will generate:
483 <p>This is a normal paragraph:</p>
485 <pre><code>This is a code block.
488 One level of indentation -- 4 spaces or 1 tab -- is removed from each
489 line of the code block. For example, this:
491 Here is an example of AppleScript:
493 tell application "Foo"
499 <p>Here is an example of AppleScript:</p>
501 <pre><code>tell application "Foo"
506 A code block continues until it reaches a line that is not indented
507 (or the end of the article).
509 Within a code block, ampersands (`&`) and angle brackets (`<` and `>`)
510 are automatically converted into HTML entities. This makes it very
511 easy to include example HTML source code using Markdown -- just paste
512 it and indent it, and Markdown will handle the hassle of encoding the
513 ampersands and angle brackets. For example, this:
516 © 2004 Foo Corporation
521 <pre><code><div class="footer">
522 &copy; 2004 Foo Corporation
526 Regular Markdown syntax is not processed within code blocks. E.g.,
527 asterisks are just literal asterisks within a code block. This means
528 it's also easy to use Markdown to write about Markdown's own syntax.
532 <h3 id="hr">Horizontal Rules</h3>
534 You can produce a horizontal rule tag (`<hr />`) by placing three or
535 more hyphens, asterisks, or underscores on a line by themselves. If you
536 wish, you may use spaces between the hyphens or asterisks. Each of the
537 following lines will produce a horizontal rule:
547 ---------------------------------------
554 <h2 id="span">Span Elements</h2>
556 <h3 id="link">Links</h3>
558 Markdown supports two style of links: *inline* and *reference*.
560 In both styles, the link text is delimited by [square brackets].
562 To create an inline link, use a set of regular parentheses immediately
563 after the link text's closing square bracket. Inside the parentheses,
564 put the URL where you want the link to point, along with an *optional*
565 title for the link, surrounded in quotes. For example:
567 This is [an example](http://example.com/ "Title") inline link.
569 [This link](http://example.net/) has no title attribute.
573 <p>This is <a href="http://example.com/" title="Title">
574 an example</a> inline link.</p>
576 <p><a href="http://example.net/">This link</a> has no
579 If you're referring to a local resource on the same server, you can
582 See my [About](/about/) page for details.
584 Reference-style links use a second set of square brackets, inside
585 which you place a label of your choosing to identify the link:
587 This is [an example][id] reference-style link.
589 You can optionally use a space to separate the sets of brackets:
591 This is [an example] [id] reference-style link.
593 Then, anywhere in the document, you define your link label like this,
596 [id]: http://example.com/ "Optional Title Here"
600 * Square brackets containing the link identifier (optionally
601 indented from the left margin using up to three spaces);
602 * followed by a colon;
603 * followed by one or more spaces (or tabs);
604 * followed by the URL for the link;
605 * optionally followed by a title attribute for the link, enclosed
606 in double or single quotes.
608 The link URL may, optionally, be surrounded by angle brackets:
610 [id]: <http://example.com/> "Optional Title Here"
612 You can put the title attribute on the next line and use extra spaces
613 or tabs for padding, which tends to look better with longer URLs:
615 [id]: http://example.com/longish/path/to/resource/here
616 "Optional Title Here"
618 Link definitions are only used for creating links during Markdown
619 processing, and are stripped from your document in the HTML output.
621 Link definition names may constist of letters, numbers, spaces, and punctuation -- but they are *not* case sensitive. E.g. these two links:
628 The *implicit link name* shortcut allows you to omit the name of the
629 link, in which case the link text itself is used as the name.
630 Just use an empty set of square brackets -- e.g., to link the word
631 "Google" to the google.com web site, you could simply write:
635 And then define the link:
637 [Google]: http://google.com/
639 Because link names may contain spaces, this shortcut even works for
640 multiple words in the link text:
642 Visit [Daring Fireball][] for more information.
644 And then define the link:
646 [Daring Fireball]: http://daringfireball.net/
648 Link definitions can be placed anywhere in your Markdown document. I
649 tend to put them immediately after each paragraph in which they're
650 used, but if you want, you can put them all at the end of your
651 document, sort of like footnotes.
653 Here's an example of reference links in action:
655 I get 10 times more traffic from [Google] [1] than from
656 [Yahoo] [2] or [MSN] [3].
658 [1]: http://google.com/ "Google"
659 [2]: http://search.yahoo.com/ "Yahoo Search"
660 [3]: http://search.msn.com/ "MSN Search"
662 Using the implicit link name shortcut, you could instead write:
664 I get 10 times more traffic from [Google][] than from
665 [Yahoo][] or [MSN][].
667 [google]: http://google.com/ "Google"
668 [yahoo]: http://search.yahoo.com/ "Yahoo Search"
669 [msn]: http://search.msn.com/ "MSN Search"
671 Both of the above examples will produce the following HTML output:
673 <p>I get 10 times more traffic from <a href="http://google.com/"
674 title="Google">Google</a> than from
675 <a href="http://search.yahoo.com/" title="Yahoo Search">Yahoo</a>
676 or <a href="http://search.msn.com/" title="MSN Search">MSN</a>.</p>
678 For comparison, here is the same paragraph written using
679 Markdown's inline link style:
681 I get 10 times more traffic from [Google](http://google.com/ "Google")
682 than from [Yahoo](http://search.yahoo.com/ "Yahoo Search") or
683 [MSN](http://search.msn.com/ "MSN Search").
685 The point of reference-style links is not that they're easier to
686 write. The point is that with reference-style links, your document
687 source is vastly more readable. Compare the above examples: using
688 reference-style links, the paragraph itself is only 81 characters
689 long; with inline-style links, it's 176 characters; and as raw HTML,
690 it's 234 characters. In the raw HTML, there's more markup than there
693 With Markdown's reference-style links, a source document much more
694 closely resembles the final output, as rendered in a browser. By
695 allowing you to move the markup-related metadata out of the paragraph,
696 you can add links without interrupting the narrative flow of your
700 <h3 id="em">Emphasis</h3>
702 Markdown treats asterisks (`*`) and underscores (`_`) as indicators of
703 emphasis. Text wrapped with one `*` or `_` will be wrapped with an
704 HTML `<em>` tag; double `*`'s or `_`'s will be wrapped with an HTML
705 `<strong>` tag. E.g., this input:
713 __double underscores__
717 <em>single asterisks</em>
719 <em>single underscores</em>
721 <strong>double asterisks</strong>
723 <strong>double underscores</strong>
725 You can use whichever style you prefer; the lone restriction is that
726 the same character must be used to open and close an emphasis span.
728 Emphasis can be used in the middle of a word:
730 un*fucking*believable
732 But if you surround an `*` or `_` with spaces, it'll be treated as a
733 literal asterisk or underscore.
735 To produce a literal asterisk or underscore at a position where it
736 would otherwise be used as an emphasis delimiter, you can backslash
739 \*this text is surrounded by literal asterisks\*
743 <h3 id="code">Code</h3>
745 To indicate a span of code, wrap it with backtick quotes (`` ` ``).
746 Unlike a pre-formatted code block, a code span indicates code within a
747 normal paragraph. For example:
749 Use the `printf()` function.
753 <p>Use the <code>printf()</code> function.</p>
755 To include a literal backtick character within a code span, you can use
756 multiple backticks as the opening and closing delimiters:
758 ``There is a literal backtick (`) here.``
760 which will produce this:
762 <p><code>There is a literal backtick (`) here.</code></p>
764 The backtick delimiters surrounding a code span may include spaces --
765 one after the opening, one before the closing. This allows you to place
766 literal backtick characters at the beginning or end of a code span:
768 A single backtick in a code span: `` ` ``
770 A backtick-delimited string in a code span: `` `foo` ``
774 <p>A single backtick in a code span: <code>`</code></p>
776 <p>A backtick-delimited string in a code span: <code>`foo`</code></p>
778 With a code span, ampersands and angle brackets are encoded as HTML
779 entities automatically, which makes it easy to include example HTML
780 tags. Markdown will turn this:
782 Please don't use any `<blink>` tags.
786 <p>Please don't use any <code><blink></code> tags.</p>
790 `—` is the decimal-encoded equivalent of `—`.
794 <p><code>&#8212;</code> is the decimal-encoded
795 equivalent of <code>&mdash;</code>.</p>
799 <h3 id="img">Images</h3>
801 Admittedly, it's fairly difficult to devise a "natural" syntax for
802 placing images into a plain text document format.
804 Markdown uses an image syntax that is intended to resemble the syntax
805 for links, allowing for two styles: *inline* and *reference*.
807 Inline image syntax looks like this:
809 ![Alt text](/path/to/img.jpg)
811 ![Alt text](/path/to/img.jpg "Optional title")
815 * An exclamation mark: `!`;
816 * followed by a set of square brackets, containing the `alt`
817 attribute text for the image;
818 * followed by a set of parentheses, containing the URL or path to
819 the image, and an optional `title` attribute enclosed in double
822 Reference-style image syntax looks like this:
826 Where "id" is the name of a defined image reference. Image references
827 are defined using syntax identical to link references:
829 [id]: url/to/image "Optional title attribute"
831 As of this writing, Markdown has no syntax for specifying the
832 dimensions of an image; if this is important to you, you can simply
833 use regular HTML `<img>` tags.
839 <h2 id="misc">Miscellaneous</h2>
841 <h3 id="autolink">Automatic Links</h3>
843 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:
845 <http://example.com/>
847 Markdown will turn this into:
849 <a href="http://example.com/">http://example.com/</a>
851 Automatic links for email addresses work similarly, except that
852 Markdown will also perform a bit of randomized decimal and hex
853 entity-encoding to help obscure your address from address-harvesting
854 spambots. For example, Markdown will turn this:
856 <address@example.com>
858 into something like this:
860 <a href="mailto:addre
861 ss@example.co
862 m">address@exa
863 mple.com</a>
865 which will render in a browser as a clickable link to "address@example.com".
867 (This sort of entity-encoding trick will indeed fool many, if not
868 most, address-harvesting bots, but it definitely won't fool all of
869 them. It's better than nothing, but an address published in this way
870 will probably eventually start receiving spam.)
874 <h3 id="backslash">Backslash Escapes</h3>
876 Markdown allows you to use backslash escapes to generate literal
877 characters which would otherwise have special meaning in Markdown's
878 formatting syntax. For example, if you wanted to surround a word with
879 literal asterisks (instead of an HTML `<em>` tag), you can backslashes
880 before the asterisks, like this:
882 \*literal asterisks\*
884 Markdown provides backslash escapes for the following characters:
895 - minus sign (hyphen)