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1 Markdown: Syntax
────────────────────────────────────
• [Main](/projects/markdown/)
• [Basics](/projects/markdown/basics
)
• [Syntax]()
• [License](/projects/markdown/licen
se)
• [Dingus](/projects/markdown/dingus
)
• [Overview](#overview)
• [Philosophy](#philosophy)
• [Inline HTML](#html)
• [Automatic Escaping for Special
Characters](#autoescape)
• [Block Elements](#block)
• [Paragraphs and Line Breaks](#p)
• [Headers](#header)
• [Blockquotes](#blockquote)
• [Lists](#list)
• [Code Blocks](#precode)
• [Horizontal Rules](#hr)
• [Span Elements](#span)
• [Links](#link)
• [Emphasis](#em)
• [Code](#code)
• [Images](#img)
• [Miscellaneous](#misc)
• [Backslash Escapes](#backslash)
• [Automatic Links](#autolink)
Note: This document is itself
written using Markdown; you can [see
the source for it by adding '.text'
to the URL](/projects/markdown/synt
ax.text).
────────────────────────────────────
1.1 Overview
1.1.1 Philosophy
Markdown is intended to be as
easy-to-read and easy-to-write as is
feasible.
Readability, however, is emphasized
above all else. A Markdown-formatted
document should be publishable
as-is, as plain text, without
looking like it's been marked up
with tags or formatting
instructions. While Markdown's
syntax has been influenced by
several existing text-to-HTML
filters -- including [Setext](http:/
/docutils.sourceforge.net/mirror/set
ext.html), [atx](http://www.aaronsw.
com/2002/atx/), [Textile](http://tex
tism.com/tools/textile/), [reStructu
redText](http://docutils.sourceforge
.net/rst.html), [Grutatext](http://w
ww.triptico.com/software/grutatxt.ht
ml), and [EtText](http://ettext.tain
t.org/doc/) -- the single biggest
source of inspiration for Markdown's
syntax is the format of plain text
email.
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.
1.1.2 Inline HTML
Markdown's syntax is intended for
one purpose: to be used as a format
for writing for the web.
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 not 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 publishing
format; Markdown is a writing
format. Thus, Markdown's formatting
syntax only addresses issues that
can be conveyed in plain text.
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.
The only restrictions are that
block-level HTML elements -- e.g.
<div>, <table>, <pre>, <p>, 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) <p> tags
around HTML block-level tags.
For example, to add an HTML table to
a Markdown article:
┃ This is a regular paragraph.
┃
┃ <table>
┃ <tr>
┃ <td>Foo</td>
┃ </tr>
┃ </table>
┃
┃ This is another regular paragraph.
Note that Markdown formatting syntax
is not processed within block-level
HTML tags. E.g., you can't use
Markdown-style *emphasis* inside an
HTML block.
Span-level HTML tags -- e.g. <span>,
<cite>, or <del> -- 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 <a> or
<img> tags instead of Markdown's
link or image syntax, go right
ahead.
Unlike block-level HTML tags,
Markdown syntax is processed within
span-level tags.
1.1.3 Automatic Escaping for Special
Characters
In HTML, there are two characters
that demand special treatment: < and
&. 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.
<, and &.
Ampersands in particular are
bedeviling for web writers. If you
want to write about 'AT&T', you need
to write 'AT&T'. You even need
to escape ampersands within URLs.
Thus, if you want to link to:
┃ http://images.google.com/images?nu
┃ m=30&q=larry+bird
you need to encode the URL as:
┃ http://images.google.com/images?nu
┃ m=30&q=larry+bird
in your anchor tag href 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.
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 &.
So, if you want to include a
copyright symbol in your article,
you can write:
┃ ©
and Markdown will leave it alone.
But if you write:
┃ AT&T
Markdown will translate it to:
┃ AT&T
Similarly, because Markdown supports
[inline HTML](#html), if you use
angle brackets as delimiters for
HTML tags, Markdown will treat them
as such. But if you write:
┃ 4 < 5
Markdown will translate it to:
┃ 4 < 5
However, inside Markdown code spans
and blocks, angle brackets and
ampersands are always 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 < and & in your example code
needs to be escaped.)
────────────────────────────────────
1.2 Block Elements
1.2.1 Paragraphs and Line Breaks
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.
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 <br /> tag.
When you do want to insert a <br />
break tag using Markdown, you end a
line with two or more spaces, then
type return.
Yes, this takes a tad more effort to
create a <br />, but a simplistic
"every line break is a <br />" rule
wouldn't work for Markdown.
Markdown's email-style
[blockquoting](#blockquote) and
multi-paragraph [list items](#list)
work best -- and look better -- when
you format them with hard breaks.
1.2.2 Headers
Markdown supports two styles of
headers, [Setext](http://docutils.so
urceforge.net/mirror/setext.html)
and [atx](http://www.aaronsw.com/200
2/atx/).
Setext-style headers are
"underlined" using equal signs (for
first-level headers) and dashes (for
second-level headers). For example:
┃ This is an H1
┃ =============
┃
┃ This is an H2
┃ -------------
Any number of underlining ='s or -'s
will work.
Atx-style headers use 1-6 hash
characters at the start of the line,
corresponding to header levels 1-6.
For example:
┃ # This is an H1
┃
┃ ## This is an H2
┃
┃ ###### This is an H6
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.)
:
┃ # This is an H1 #
┃
┃ ## This is an H2 ##
┃
┃ ### This is an H3 ######
1.2.3 Blockquotes
Markdown uses email-style >
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 > before every line:
┃ > 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.
Markdown allows you to be lazy and
only put the > before the first line
of a hard-wrapped paragraph:
┃ > 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.
Blockquotes can be nested (i.e. a
blockquote-in-a-blockquote) by
adding additional levels of >:
┃ > This is the first level of
┃ quoting.
┃ >
┃ > > This is nested blockquote.
┃ >
┃ > Back to the first level.
Blockquotes can contain other
Markdown elements, including
headers, lists, and code blocks:
┃ > ## 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");
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.
1.2.4 Lists
Markdown supports ordered (numbered)
and unordered (bulleted) lists.
Unordered lists use asterisks,
pluses, and hyphens --
interchangably -- as list markers:
┃ * Red
┃ * Green
┃ * Blue
is equivalent to:
┃ + Red
┃ + Green
┃ + Blue
and:
┃ - Red
┃ - Green
┃ - Blue
Ordered lists use numbers followed
by periods:
┃ 1. Bird
┃ 2. McHale
┃ 3. Parish
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:
┃ <ol>
┃ <li>Bird</li>
┃ <li>McHale</li>
┃ <li>Parish</li>
┃ </ol>
If you instead wrote the list in
Markdown like this:
┃ 1. Bird
┃ 1. McHale
┃ 1. Parish
or even:
┃ 3. Bird
┃ 1. McHale
┃ 8. Parish
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.
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.
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.
To make lists look nice, you can
wrap items with hanging indents:
┃ * 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.
But if you want to be lazy, you
don't have to:
┃ * 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.
If list items are separated by blank
lines, Markdown will wrap the items
in <p> tags in the HTML output. For
example, this input:
┃ * Bird
┃ * Magic
will turn into:
┃ <ul>
┃ <li>Bird</li>
┃ <li>Magic</li>
┃ </ul>
But this:
┃ * Bird
┃
┃ * Magic
will turn into:
┃ <ul>
┃ <li><p>Bird</p></li>
┃ <li><p>Magic</p></li>
┃ </ul>
List items may consist of multiple
paragraphs. Each subsequent
paragraph in a list item must be
intended by either 4 spaces or one
tab:
┃ 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.
It looks nice if you indent every
line of the subsequent paragraphs,
but here again, Markdown will allow
you to be lazy:
┃ * 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.
To put a blockquote within a list
item, the blockquote's > delimiters
need to be indented:
┃ * A list item with a blockquote:
┃
┃ > This is a blockquote
┃ > inside a list item.
To put a code block within a list
item, the code block needs to be
indented twice -- 8 spaces or two
tabs:
┃ * A list item with a code block:
┃
┃ <code goes here>
It's worth noting that it's possible
to trigger an ordered list by
accident, by writing something like
this:
┃ 1986. What a great season.
In other words, a
number-period-space sequence at the
beginning of a line. To avoid this,
you can backslash-escape the period:
┃ 1986\. What a great season.
1.2.5 Code Blocks
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 <pre> and <code> tags.
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:
┃ This is a normal paragraph:
┃
┃ This is a code block.
Markdown will generate:
┃ <p>This is a normal paragraph:</p>
┃
┃ <pre><code>This is a code block.
┃ </code></pre>
One level of indentation -- 4 spaces
or 1 tab -- is removed from each
line of the code block. For example,
this:
┃ Here is an example of AppleScript:
┃
┃ tell application "Foo"
┃ beep
┃ end tell
will turn into:
┃ <p>Here is an example of
┃ AppleScript:</p>
┃
┃ <pre><code>tell application "Foo"
┃ beep
┃ end tell
┃ </code></pre>
A code block continues until it
reaches a line that is not indented
(or the end of the article).
Within a code block, ampersands (&)
and angle brackets (< and >) 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:
┃ <div class="footer">
┃ © 2004 Foo
┃ Corporation
┃ </div>
will turn into:
┃ <pre><code><div
┃ class="footer">
┃ &copy; 2004 Foo
┃ Corporation
┃ </div>
┃ </code></pre>
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.
1.2.6 Horizontal Rules
You can produce a horizontal rule
tag (<hr />) 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:
┃ * * *
┃
┃ ***
┃
┃ *****
┃
┃ - - -
┃
┃ ----------------------------------
┃ -----
┃
┃ _ _ _
────────────────────────────────────
1.3 Span Elements
1.3.1 Links
Markdown supports two style of
links: inline and reference.
In both styles, the link text is
delimited by [square brackets].
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 optional
title for the link, surrounded in
quotes. For example:
┃ This is [an
┃ example](http://example.com/
┃ "Title") inline link.
┃
┃ [This link](http://example.net/)
┃ has no title attribute.
Will produce:
┃ <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>
If you're referring to a local
resource on the same server, you can
use relative paths:
┃ See my [About](/about/) page for
┃ details.
Reference-style links use a second
set of square brackets, inside which
you place a label of your choosing
to identify the link:
┃ This is [an example][id]
┃ reference-style link.
You can optionally use a space to
separate the sets of brackets:
┃ This is [an example] [id]
┃ reference-style link.
Then, anywhere in the document, you
define your link label like this, on
a line by itself:
┃ [id]: http://example.com/
┃ "Optional Title Here"
That is:
• Square brackets containing the
link identifier (optionally
indented from the left margin
using up to three spaces);
• followed by a colon;
• followed by one or more spaces (or
tabs);
• followed by the URL for the link;
• optionally followed by a title
attribute for the link, enclosed
in double or single quotes.
The link URL may, optionally, be
surrounded by angle brackets:
┃ [id]: <http://example.com/>
┃ "Optional Title Here"
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:
┃ [id]: http://example.com/longish/p
┃ ath/to/resource/here
┃ "Optional Title Here"
Link definitions are only used for
creating links during Markdown
processing, and are stripped from
your document in the HTML output.
Link definition names may constist
of letters, numbers, spaces, and
punctuation -- but they are not case
sensitive. E.g. these two links:
┃ [link text][a]
┃ [link text][A]
are equivalent.
The implicit link name 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:
┃ [Google][]
And then define the link:
┃ [Google]: http://google.com/
Because link names may contain
spaces, this shortcut even works for
multiple words in the link text:
┃ Visit [Daring Fireball][] for more
┃ information.
And then define the link:
┃ [Daring Fireball]:
┃ http://daringfireball.net/
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.
Here's an example of reference links
in action:
┃ 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"
Using the implicit link name
shortcut, you could instead write:
┃ 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"
Both of the above examples will
produce the following HTML output:
┃ <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>
For comparison, here is the same
paragraph written using Markdown's
inline link style:
┃ 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").
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.
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.
1.3.2 Emphasis
Markdown treats asterisks (*) and
underscores (_) as indicators of
emphasis. Text wrapped with one * or
_ will be wrapped with an HTML <em>
tag; double *'s or _'s will be
wrapped with an HTML <strong> tag.
E.g., this input:
┃ *single asterisks*
┃
┃ _single underscores_
┃
┃ **double asterisks**
┃
┃ __double underscores__
will produce:
┃ <em>single asterisks</em>
┃
┃ <em>single underscores</em>
┃
┃ <strong>double asterisks</strong>
┃
┃ <strong>double
┃ underscores</strong>
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.
Emphasis can be used in the middle
of a word:
┃ un*fucking*believable
But if you surround an * or _ with
spaces, it'll be treated as a
literal asterisk or underscore.
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:
┃ \*this text is surrounded by
┃ literal asterisks\*
1.3.3 Code
To indicate a span of code, wrap it
with backtick quotes (`). Unlike a
pre-formatted code block, a code
span indicates code within a normal
paragraph. For example:
┃ Use the `printf()` function.
will produce:
┃ <p>Use the <code>printf()</code>
┃ function.</p>
To include a literal backtick
character within a code span, you
can use multiple backticks as the
opening and closing delimiters:
┃ ``There is a literal backtick (`)
┃ here.``
which will produce this:
┃ <p><code>There is a literal
┃ backtick (`) here.</code></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:
┃ A single backtick in a code span:
┃ `` ` ``
┃
┃ A backtick-delimited string in a
┃ code span: `` `foo` ``
┃
will produce:
┃ <p>A single backtick in a code
┃ span: <code>`</code></p>
┃
┃ <p>A backtick-delimited string in
┃ a code span:
┃ <code>`foo`</code></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:
┃ Please don't use any `<blink>`
┃ tags.
into:
┃ <p>Please don't use any
┃ <code><blink></code>
┃ tags.</p>
You can write this:
┃ `—` is the decimal-encoded
┃ equivalent of `—`.
to produce:
┃ <p><code>&#8212;</code> is the
┃ decimal-encoded
┃ equivalent of
┃ <code>&mdash;</code>.</p>
1.3.4 Images
Admittedly, it's fairly difficult to
devise a "natural" syntax for
placing images into a plain text
document format.
Markdown uses an image syntax that
is intended to resemble the syntax
for links, allowing for two styles:
inline and reference.
Inline image syntax looks like this:
┃ 
┃
┃ 
That is:
• An exclamation mark: !;
• followed by a set of square
brackets, containing the alt
attribute text for the image;
• followed by a set of parentheses,
containing the URL or path to the
image, and an optional title
attribute enclosed in double or
single quotes.
Reference-style image syntax looks
like this:
┃ ![Alt text][id]
Where "id" is the name of a defined
image reference. Image references
are defined using syntax identical
to link references:
┃ [id]: url/to/image "Optional
┃ title attribute"
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 <img> tags.
────────────────────────────────────
1.4 Miscellaneous
1.4.1 Automatic Links
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:
┃ <http://example.com/>
Markdown will turn this into:
┃ <a href="http://example.com/">http
┃ ://example.com/</a>
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:
┃ <[email protected]>
into something like this:
┃ <a href="mailt
┃ o:addr&#x
┃ 65;
┃ ss@exa
┃ ;mple.c
┃ 11;
┃ m">addr&#
┃ x65;ss@ex&
┃ #x61;
┃ mple.c
┃ 1;m</a>
which will render in a browser as a
clickable link to
"[email protected]".
(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.)
1.4.2 Backslash Escapes
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 <em> tag), you can backslashes
before the asterisks, like this:
┃ \*literal asterisks\*
Markdown provides backslash escapes
for the following characters:
┃ \ backslash
┃ ` backtick
┃ * asterisk
┃ _ underscore
┃ {} curly braces
┃ [] square brackets
┃ () parentheses
┃ # hash mark
┃ + plus sign
┃ - minus sign (hyphen)
┃ . dot
┃ ! exclamation mark
────────────────────────────────────
• [Main](/projects/markdown/)
• [Basics](/projects/markdown/basics
)
• [Syntax]()
• [License](/projects/markdown/licen
se)
• [Dingus](/projects/markdown/dingus
)
• [Overview](#overview)
• [Philosophy](#philosophy)
• [Inline HTML](#html)
• [Automatic Escaping for Special
Characters](#autoescape)
• [Block Elements](#block)
• [Paragraphs and Line Breaks](#p)
• [Headers](#header)
• [Blockquotes](#blockquote)
• [Lists](#list)
• [Code Blocks](#precode)
• [Horizontal Rules](#hr)
• [Span Elements](#span)
• [Links](#link)
• [Emphasis](#em)
• [Code](#code)
• [Images](#img)
• [Miscellaneous](#misc)
• [Backslash Escapes](#backslash)
• [Automatic Links](#autolink)
Note: This document is itself
written using Markdown; you can [see
the source for it by adding '.text'
to the URL](/projects/markdown/synt
ax.text).
────────────────────────────────────
1.1 Overview
1.1.1 Philosophy
Markdown is intended to be as
easy-to-read and easy-to-write as is
feasible.
Readability, however, is emphasized
above all else. A Markdown-formatted
document should be publishable
as-is, as plain text, without
looking like it's been marked up
with tags or formatting
instructions. While Markdown's
syntax has been influenced by
several existing text-to-HTML
filters -- including [Setext](http:/
/docutils.sourceforge.net/mirror/set
ext.html), [atx](http://www.aaronsw.
com/2002/atx/), [Textile](http://tex
tism.com/tools/textile/), [reStructu
redText](http://docutils.sourceforge
.net/rst.html), [Grutatext](http://w
ww.triptico.com/software/grutatxt.ht
ml), and [EtText](http://ettext.tain
t.org/doc/) -- the single biggest
source of inspiration for Markdown's
syntax is the format of plain text
email.
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.
1.1.2 Inline HTML
Markdown's syntax is intended for
one purpose: to be used as a format
for writing for the web.
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 not 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 publishing
format; Markdown is a writing
format. Thus, Markdown's formatting
syntax only addresses issues that
can be conveyed in plain text.
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.
The only restrictions are that
block-level HTML elements -- e.g.
<div>, <table>, <pre>, <p>, 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) <p> tags
around HTML block-level tags.
For example, to add an HTML table to
a Markdown article:
┃ This is a regular paragraph.
┃
┃ <table>
┃ <tr>
┃ <td>Foo</td>
┃ </tr>
┃ </table>
┃
┃ This is another regular paragraph.
Note that Markdown formatting syntax
is not processed within block-level
HTML tags. E.g., you can't use
Markdown-style *emphasis* inside an
HTML block.
Span-level HTML tags -- e.g. <span>,
<cite>, or <del> -- 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 <a> or
<img> tags instead of Markdown's
link or image syntax, go right
ahead.
Unlike block-level HTML tags,
Markdown syntax is processed within
span-level tags.
1.1.3 Automatic Escaping for Special
Characters
In HTML, there are two characters
that demand special treatment: < and
&. 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.
<, and &.
Ampersands in particular are
bedeviling for web writers. If you
want to write about 'AT&T', you need
to write 'AT&T'. You even need
to escape ampersands within URLs.
Thus, if you want to link to:
┃ http://images.google.com/images?nu
┃ m=30&q=larry+bird
you need to encode the URL as:
┃ http://images.google.com/images?nu
┃ m=30&q=larry+bird
in your anchor tag href 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.
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 &.
So, if you want to include a
copyright symbol in your article,
you can write:
┃ ©
and Markdown will leave it alone.
But if you write:
┃ AT&T
Markdown will translate it to:
┃ AT&T
Similarly, because Markdown supports
[inline HTML](#html), if you use
angle brackets as delimiters for
HTML tags, Markdown will treat them
as such. But if you write:
┃ 4 < 5
Markdown will translate it to:
┃ 4 < 5
However, inside Markdown code spans
and blocks, angle brackets and
ampersands are always 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 < and & in your example code
needs to be escaped.)
────────────────────────────────────
1.2 Block Elements
1.2.1 Paragraphs and Line Breaks
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.
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 <br /> tag.
When you do want to insert a <br />
break tag using Markdown, you end a
line with two or more spaces, then
type return.
Yes, this takes a tad more effort to
create a <br />, but a simplistic
"every line break is a <br />" rule
wouldn't work for Markdown.
Markdown's email-style
[blockquoting](#blockquote) and
multi-paragraph [list items](#list)
work best -- and look better -- when
you format them with hard breaks.
1.2.2 Headers
Markdown supports two styles of
headers, [Setext](http://docutils.so
urceforge.net/mirror/setext.html)
and [atx](http://www.aaronsw.com/200
2/atx/).
Setext-style headers are
"underlined" using equal signs (for
first-level headers) and dashes (for
second-level headers). For example:
┃ This is an H1
┃ =============
┃
┃ This is an H2
┃ -------------
Any number of underlining ='s or -'s
will work.
Atx-style headers use 1-6 hash
characters at the start of the line,
corresponding to header levels 1-6.
For example:
┃ # This is an H1
┃
┃ ## This is an H2
┃
┃ ###### This is an H6
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.)
:
┃ # This is an H1 #
┃
┃ ## This is an H2 ##
┃
┃ ### This is an H3 ######
1.2.3 Blockquotes
Markdown uses email-style >
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 > before every line:
┃ > 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.
Markdown allows you to be lazy and
only put the > before the first line
of a hard-wrapped paragraph:
┃ > 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.
Blockquotes can be nested (i.e. a
blockquote-in-a-blockquote) by
adding additional levels of >:
┃ > This is the first level of
┃ quoting.
┃ >
┃ > > This is nested blockquote.
┃ >
┃ > Back to the first level.
Blockquotes can contain other
Markdown elements, including
headers, lists, and code blocks:
┃ > ## 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");
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.
1.2.4 Lists
Markdown supports ordered (numbered)
and unordered (bulleted) lists.
Unordered lists use asterisks,
pluses, and hyphens --
interchangably -- as list markers:
┃ * Red
┃ * Green
┃ * Blue
is equivalent to:
┃ + Red
┃ + Green
┃ + Blue
and:
┃ - Red
┃ - Green
┃ - Blue
Ordered lists use numbers followed
by periods:
┃ 1. Bird
┃ 2. McHale
┃ 3. Parish
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:
┃ <ol>
┃ <li>Bird</li>
┃ <li>McHale</li>
┃ <li>Parish</li>
┃ </ol>
If you instead wrote the list in
Markdown like this:
┃ 1. Bird
┃ 1. McHale
┃ 1. Parish
or even:
┃ 3. Bird
┃ 1. McHale
┃ 8. Parish
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.
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.
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.
To make lists look nice, you can
wrap items with hanging indents:
┃ * 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.
But if you want to be lazy, you
don't have to:
┃ * 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.
If list items are separated by blank
lines, Markdown will wrap the items
in <p> tags in the HTML output. For
example, this input:
┃ * Bird
┃ * Magic
will turn into:
┃ <ul>
┃ <li>Bird</li>
┃ <li>Magic</li>
┃ </ul>
But this:
┃ * Bird
┃
┃ * Magic
will turn into:
┃ <ul>
┃ <li><p>Bird</p></li>
┃ <li><p>Magic</p></li>
┃ </ul>
List items may consist of multiple
paragraphs. Each subsequent
paragraph in a list item must be
intended by either 4 spaces or one
tab:
┃ 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.
It looks nice if you indent every
line of the subsequent paragraphs,
but here again, Markdown will allow
you to be lazy:
┃ * 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.
To put a blockquote within a list
item, the blockquote's > delimiters
need to be indented:
┃ * A list item with a blockquote:
┃
┃ > This is a blockquote
┃ > inside a list item.
To put a code block within a list
item, the code block needs to be
indented twice -- 8 spaces or two
tabs:
┃ * A list item with a code block:
┃
┃ <code goes here>
It's worth noting that it's possible
to trigger an ordered list by
accident, by writing something like
this:
┃ 1986. What a great season.
In other words, a
number-period-space sequence at the
beginning of a line. To avoid this,
you can backslash-escape the period:
┃ 1986\. What a great season.
1.2.5 Code Blocks
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 <pre> and <code> tags.
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:
┃ This is a normal paragraph:
┃
┃ This is a code block.
Markdown will generate:
┃ <p>This is a normal paragraph:</p>
┃
┃ <pre><code>This is a code block.
┃ </code></pre>
One level of indentation -- 4 spaces
or 1 tab -- is removed from each
line of the code block. For example,
this:
┃ Here is an example of AppleScript:
┃
┃ tell application "Foo"
┃ beep
┃ end tell
will turn into:
┃ <p>Here is an example of
┃ AppleScript:</p>
┃
┃ <pre><code>tell application "Foo"
┃ beep
┃ end tell
┃ </code></pre>
A code block continues until it
reaches a line that is not indented
(or the end of the article).
Within a code block, ampersands (&)
and angle brackets (< and >) 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:
┃ <div class="footer">
┃ © 2004 Foo
┃ Corporation
┃ </div>
will turn into:
┃ <pre><code><div
┃ class="footer">
┃ &copy; 2004 Foo
┃ Corporation
┃ </div>
┃ </code></pre>
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.
1.2.6 Horizontal Rules
You can produce a horizontal rule
tag (<hr />) 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:
┃ * * *
┃
┃ ***
┃
┃ *****
┃
┃ - - -
┃
┃ ----------------------------------
┃ -----
┃
┃ _ _ _
────────────────────────────────────
1.3 Span Elements
1.3.1 Links
Markdown supports two style of
links: inline and reference.
In both styles, the link text is
delimited by [square brackets].
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 optional
title for the link, surrounded in
quotes. For example:
┃ This is [an
┃ example](http://example.com/
┃ "Title") inline link.
┃
┃ [This link](http://example.net/)
┃ has no title attribute.
Will produce:
┃ <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>
If you're referring to a local
resource on the same server, you can
use relative paths:
┃ See my [About](/about/) page for
┃ details.
Reference-style links use a second
set of square brackets, inside which
you place a label of your choosing
to identify the link:
┃ This is [an example][id]
┃ reference-style link.
You can optionally use a space to
separate the sets of brackets:
┃ This is [an example] [id]
┃ reference-style link.
Then, anywhere in the document, you
define your link label like this, on
a line by itself:
┃ [id]: http://example.com/
┃ "Optional Title Here"
That is:
• Square brackets containing the
link identifier (optionally
indented from the left margin
using up to three spaces);
• followed by a colon;
• followed by one or more spaces (or
tabs);
• followed by the URL for the link;
• optionally followed by a title
attribute for the link, enclosed
in double or single quotes.
The link URL may, optionally, be
surrounded by angle brackets:
┃ [id]: <http://example.com/>
┃ "Optional Title Here"
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:
┃ [id]: http://example.com/longish/p
┃ ath/to/resource/here
┃ "Optional Title Here"
Link definitions are only used for
creating links during Markdown
processing, and are stripped from
your document in the HTML output.
Link definition names may constist
of letters, numbers, spaces, and
punctuation -- but they are not case
sensitive. E.g. these two links:
┃ [link text][a]
┃ [link text][A]
are equivalent.
The implicit link name 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:
┃ [Google][]
And then define the link:
┃ [Google]: http://google.com/
Because link names may contain
spaces, this shortcut even works for
multiple words in the link text:
┃ Visit [Daring Fireball][] for more
┃ information.
And then define the link:
┃ [Daring Fireball]:
┃ http://daringfireball.net/
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.
Here's an example of reference links
in action:
┃ 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"
Using the implicit link name
shortcut, you could instead write:
┃ 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"
Both of the above examples will
produce the following HTML output:
┃ <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>
For comparison, here is the same
paragraph written using Markdown's
inline link style:
┃ 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").
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.
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.
1.3.2 Emphasis
Markdown treats asterisks (*) and
underscores (_) as indicators of
emphasis. Text wrapped with one * or
_ will be wrapped with an HTML <em>
tag; double *'s or _'s will be
wrapped with an HTML <strong> tag.
E.g., this input:
┃ *single asterisks*
┃
┃ _single underscores_
┃
┃ **double asterisks**
┃
┃ __double underscores__
will produce:
┃ <em>single asterisks</em>
┃
┃ <em>single underscores</em>
┃
┃ <strong>double asterisks</strong>
┃
┃ <strong>double
┃ underscores</strong>
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.
Emphasis can be used in the middle
of a word:
┃ un*fucking*believable
But if you surround an * or _ with
spaces, it'll be treated as a
literal asterisk or underscore.
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:
┃ \*this text is surrounded by
┃ literal asterisks\*
1.3.3 Code
To indicate a span of code, wrap it
with backtick quotes (`). Unlike a
pre-formatted code block, a code
span indicates code within a normal
paragraph. For example:
┃ Use the `printf()` function.
will produce:
┃ <p>Use the <code>printf()</code>
┃ function.</p>
To include a literal backtick
character within a code span, you
can use multiple backticks as the
opening and closing delimiters:
┃ ``There is a literal backtick (`)
┃ here.``
which will produce this:
┃ <p><code>There is a literal
┃ backtick (`) here.</code></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:
┃ A single backtick in a code span:
┃ `` ` ``
┃
┃ A backtick-delimited string in a
┃ code span: `` `foo` ``
┃
will produce:
┃ <p>A single backtick in a code
┃ span: <code>`</code></p>
┃
┃ <p>A backtick-delimited string in
┃ a code span:
┃ <code>`foo`</code></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:
┃ Please don't use any `<blink>`
┃ tags.
into:
┃ <p>Please don't use any
┃ <code><blink></code>
┃ tags.</p>
You can write this:
┃ `—` is the decimal-encoded
┃ equivalent of `—`.
to produce:
┃ <p><code>&#8212;</code> is the
┃ decimal-encoded
┃ equivalent of
┃ <code>&mdash;</code>.</p>
1.3.4 Images
Admittedly, it's fairly difficult to
devise a "natural" syntax for
placing images into a plain text
document format.
Markdown uses an image syntax that
is intended to resemble the syntax
for links, allowing for two styles:
inline and reference.
Inline image syntax looks like this:
┃ 
┃
┃ 
That is:
• An exclamation mark: !;
• followed by a set of square
brackets, containing the alt
attribute text for the image;
• followed by a set of parentheses,
containing the URL or path to the
image, and an optional title
attribute enclosed in double or
single quotes.
Reference-style image syntax looks
like this:
┃ ![Alt text][id]
Where "id" is the name of a defined
image reference. Image references
are defined using syntax identical
to link references:
┃ [id]: url/to/image "Optional
┃ title attribute"
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 <img> tags.
────────────────────────────────────
1.4 Miscellaneous
1.4.1 Automatic Links
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:
┃ <http://example.com/>
Markdown will turn this into:
┃ <a href="http://example.com/">http
┃ ://example.com/</a>
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:
┃ <[email protected]>
into something like this:
┃ <a href="mailt
┃ o:addr&#x
┃ 65;
┃ ss@exa
┃ ;mple.c
┃ 11;
┃ m">addr&#
┃ x65;ss@ex&
┃ #x61;
┃ mple.c
┃ 1;m</a>
which will render in a browser as a
clickable link to
"[email protected]".
(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.)
1.4.2 Backslash Escapes
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 <em> tag), you can backslashes
before the asterisks, like this:
┃ \*literal asterisks\*
Markdown provides backslash escapes
for the following characters:
┃ \ backslash
┃ ` backtick
┃ * asterisk
┃ _ underscore
┃ {} curly braces
┃ [] square brackets
┃ () parentheses
┃ # hash mark
┃ + plus sign
┃ - minus sign (hyphen)
┃ . dot
┃ ! exclamation mark