Level 1 Header can use any number of equal signs
=
Level 2 Header can use any number of dashes
-
# You can also use #
## Hash marks to create header levels
### The closing hash marks are optional ###
Horizontal rules use 3 or more hyphens, asterisks or underscores
---
text
***
text
___
text
breaking up the line markers also works
* * *
A bulleted list:
- Use a dash
+ Or a plus sign
* Or an asterisk
A numbered list:
1. Numbered lists are easy
2. The numbers are automatically tracked
7. So this will be number 3
Double-spaced list:
- You can make a spaced-out list wrapped in `` tags
- By putting a space in between the lines
Nested Lists:
1. Lists in a list item:
- Indent four spaces
* Per list level
2. You can do multiple paragraphs if you skip a line.
And indent four spaces.
Three works, too but that can be confusing.
3. To put blockquotes in a list item
> Skip a line and indent the starting '>' four spaces.
4. To put preformatted code in a list item
Skip a line and indent eight spaces.
Simple Blockquotes
>Just add > to the start of the line.
>And you'll get a blockquote.
Blockquote paragraphs
> Putting a >
>
> on blank lines is optional
> it all looks the same to the markdown editor.
Blockquote nesting
>You can nest
>>blockquotes to any
>>>level you want
Lists in blockquotes
> - A list in a blockquote
> - Have to have a > and a space before the bullet marker
> * And you can do nested lists.
Code and quotes
> Just indent the text four spaces after the >
Images
Inline image: 
Reference image with tooltip: ![valid XHTML][checkmark]
You can't do this ![checkmark]
but you can do this ![checkmark][] where the ref name will be the alt text.
Regular image links also work, including scaling:
[1]: http://www.google.com
[Google]: http://www.google.com
[parens]: http://www.google.com (Click to go to Google)
[quotes]: http://www.google.com "Click for Google"
[checkmark]: http://w3.org/Icons/valid-xhtml10 "Image tooltip"