You may use tags within other tags (e.g. combining bold and italic tags). If you miss a closing tag then the format will not appear. This is to prevent all of the text appearing in italic in case you forget to close off a [i] tag for example.
Basic Formatting
Bold Tags: Use [b]example text[/b] to produce example text
Italic Tags: Use [i]example text[/i] to produce example text
Underline Tags: Use [u]example text[/u] to produce example text
Strikethrough Tags: Use [strike]example text[/strike] to produce example text
Colour Tags: Use [colour=blue]example text[/colour] to produce example text
Size Tags: Use [size=3]example text[/size] to produce example text
Small Tags: Use [small]example text[/small] to produce example text
Pre Tags: Use [pre]my notepad text etc[/pre] to produce
my notepad text etc*This preserves line breaks and spaces in notepad text and similar.
URL Formatting
URL Tags: Use [url]http://www.example.com[/url] to produce http://www.example.com
Descriptive Tags: Use [url=http://www.example.com]Example.Com[/url] to produce Example.Com