a blank line, useful on profile pages etc so your text is not all jammed together. the HTML tag to use is <br>. technically its a line break so you need to use it twice to get a empty line.
my name is john from dunedin
i enjoy tramping etc.
To add a link to another web-page.
Here is a <a href="http://www.example.com/">link</a> to a website.
For the following effect:
Here is a link to a website.
I can add more info to this article as needed, just mail me, cant co-author/share access.