The "Rank Editor" allows you to classify your members based on how many forum posts they have made. This is useful to help differentiate new forum members from those that are more experienced.
You give each rank a name and a minimum number of posts. Here is an example:
New Forum Member - minimum 1 post
Forum Ninja - minimum 100 posts
A member who posts at least once will see "New Forum Member" displayed next to their Forum Username whenever they post.
Once that member posts 100 times, they will see "Forum Ninja" displayed next to their Forum Username.