You belong to post-count-based membergroups based on the number of posts you have made. Your membership in these groups can automatically change when your number of posts changes. The administrator who can see which post-count-based membergroups the membes belong to. Every new member belongs to the Newbie membergroup. The details of the post-count based membergroups can be set at Edit Membergroups. The Newbie membergroup can never be removed.