clarifying users privileges

[mepossem]

what i want is that all users have to register with their email address etc. so that i always have some control.
is this possible?
seems it is possible on the forum

[blog.brockha.us]

Yes, this is possible. You can define read/write access to categories only for some groups, so this categories won't be readable by normal visitors but only for logged in visitors.

And as far as I remember a plugin exists, that allows to create new accounts by normal visitors.