[Marco van Herwaarden]

You can create a usergroup and set it to be Public. The user will now have the choice to join that group or, unlike a "normal" usergroup where the user don't really have the option to join a group (except paid subscriptions).

You can use this for anything that suits you, some examples:
- A male and a Female usergroup
- An Adult section, that only members who joined the adult group will see.
- If you have a big board there might be forums of totally different interest. With public groups that give you Forum Permissions to these forums, you could give the user control over which forums he see.

If you also set a Group Leader, you can have the group leader moderate who joins.

These are just some examples.