Quote:
When posting messages to the forums or other members, there are three interface types available to you. The simplest of these is a simple text box, while the last is a fully-fledged WYSIWYG editor, which allows you to format your text as you want it and see the results immediately.
So basically it makes things easier when typing out messages. To change settings for Message Editor Interface, go to your UserCP (top of page next to "Home" and "Forum") and go to "Edit Option", Scroll down, there you will see the "Message Editor Interface" title.