Each time you submit a certain number of posts, your signature "name" will change to show others how active you have been. Some people have only posted concerning a particular problem that they are dealing with at the moment, and may never be heard from again. Others find that they like the forum for whatever reason. The comradery, the ability to share experiences and knowledge, etc., these folks will be around forever.
I think it goes something like this:
this should give you the idea. You may have noticed that the number of posts someone has is listed on the right hand side of the posts.