I'm just curious as to what all the different "titles" mean under a username. Under mine it says registered user, which makes since, but I've seen some that say "member" or "senior member". What do the different titles mean?

Also, in the Members List section, there is a catagory for Reputation with the little green dots.....okay, I hold the mouse over these dots and a message will pop up saying "username is off the low scale" or "username is on a distinguished road" I'm just curious what these mean?