Help:VBulletin:Message Icons and Thread Prefixes
What are message icons?
Message Icons, also known as Post Icons, are small icons that appear in the title of your post. If your post is the first in a thread, then they also display in the thread listings. If the board administrator has enabled these, they can be found below the message box on the 'New Post' and 'New Thread' pages. Simply select the icon that you wish to use and this will be displayed before your thread title.
What are thread prefixes?
Thread Prefixes can be used to further identify your thread as containing a particular content in the forum. If your administrator has enabled these, you will see a box before the title box which contains a menu with the available prefixes for you to choose from.