Thread:Sannse/@comment-25494228-20130829005037/@comment-8-20130904184734

Someone with the "rollback" right can see links next to some edits that allow them to quickly reverse what someone has done. For example, if someone added vandalism to a page, a rollbacker could go to that person's contribution pages (or the article history, or Special:Recentchanges) and hit the rollback link to remove it.

If you are an admin, you don't need rollback rights. because you can do this already

A bureaucrat can change people's rights (although they can't remove other people's bureaucrat rights. Bureaucrats almost always have admin rights too, because otherwise changing rights is their only extra right.  It's like an add-on right that gives admins that extra ability :)