Quote Originally Posted by mutt View Post
How's restricting this section going to keep it private? Membership is free and open to everyone. If a guest wants to read that section they'll just become a member.
Forum Admins can set the permissions so that only certain forums are available to guests. Otherwise they are only available to registered members.

These restricted permissions can keep guests from accessing forum sections that the Admins want to keep private.

Some forums restrict access to Classifieds to members with a certain amount of posts in order to discourage forum trolls from ripping people off (ie they won't invest the time to get their post count up, they will move on to easier pickings elsewhere).