Markdown is a simple way to spiff up your text. It's great to use at Diaspora for adding photos you find online, linking sites or just to be irritating by posting big words. Here is a simple list, followed by a screen shot of how it should look, in the order given.
I will add, that currently, if you don't want markdown to appear accidentally in your statuses, simply use ``` on the line before your post and again, ``` at the end of your post. This little symbol is to the left hand side of your 1 on your keyboard, under that little squiggly line.
to post a link use [link name](linkurl)
to post an image, use ![image name](url of image) - be sure to include the exclamation mark
to use italics, use *yourtext*
to use bold, use **yourtext**
to use bold AND italics, use ***yourtext***
to post big headings, use ##
your text or # your text- leave space between # and your text. Not neccesary to repeat the # sign on the right side of your text.