` tags in the HTML output. For example, this input:
* Bird
* Magic
will turn into:
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.
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 `` and `` tags.
To produce a code block in Markdown, simply indent every line of the
block by at least 4 spaces or 1 tab. Alternatively precede the block with
a line consisting of 3 backtick quotes (or more) and follow it with a
line consisting of the same number of backtick quotes -- in this case the
code lines themselves do not require any additional indentation.
For example, given this input:
This is a normal paragraph:
This is a code block.
Or this equivalent input:
This is a normal paragraph.
```
This is a code block.
```
Markdown will generate:
This is a normal paragraph:
This is a code block.
Note that when using the 3 backtick quotes technique, the blank line
before the start of the code block is optional. One level of
indentation -- 4 spaces or 1 tab -- is removed from each
line of the code block unless the 3 backtick quotes are used.
For example, this:
Here is an example of AppleScript:
tell application "Foo"
beep
end tell
will turn into:
Here is an example of AppleScript:
tell application "Foo"
beep
end tell
A code block continues until it reaches a line that is not indented
(or the end of the article) when using the indentation technique or
until a line consisting of the same number of backtick quotes is found
when using the 3 backtick quotes technique.
Note that the 3 backtick quotes (or more) must appear at the beginning
of the line. To include a code block within a list (or other indented
element), the indentation technique must be used.
Also note that within a backticks-delimited code block, tab characters
are always expanded with the tab stop locations 8 characters apart.
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:
will turn into:
<div class="footer">
© 2004 Foo Corporation
</div>
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.
Horizontal Rules
You can produce a horizontal rule tag (`
`) 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:
* * *
***
*****
- - -
---------------------------------------
- - - - -
Span Elements
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:
This is
an example inline link.
This link has no
title attribute.
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, or enclosed in parentheses.
The following three link definitions are equivalent:
[foo]: http://example.com/ "Optional Title Here"
[foo]: http://example.com/ 'Optional Title Here'
[foo]: http://example.com/ (Optional Title Here)
**Note:** There is a known bug in Markdown.pl 1.0.3 which prevents
single quotes from being used to delimit link titles.
The link URL may, optionally, be surrounded by angle brackets:
[id]: "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/path/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 consist 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:
I get 10 times more traffic from Google than from
Yahoo
or MSN.
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.
Emphasis
Markdown treats asterisks (`*`) and underscores (`_`) as indicators of
emphasis. Text wrapped with one `*` or `_` will be wrapped with an
HTML `` tag; double `*`'s or `_`'s will be wrapped with an HTML
`` tag. Double `~`'s will be wrapped with an HTML `` tag.
E.g., this input:
*single asterisks*
_single underscores_
**double asterisks**
__double underscores__
~~double tildes~~
will produce:
single asterisks
single underscores
double asterisks
double underscores
strike through
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.
Additionally `_` and double `_` are not recognized within words.
Emphasis using `*`'s or `~`'s can be used in the middle of a word:
un*frigging*believable fan~~frigging~~tastic
But if you surround an `*`, `_` or `~` with spaces, it'll be treated as a
literal asterisk, underscore or tilde.
To produce a literal asterisk, underscore or tilde 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\*
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:
Use the printf() function.
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:
There is a literal backtick (`) here.
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:
A single backtick in a code span: `
A backtick-delimited string in a code span: `foo`
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 `