MediaWiki:Userrights-groups-help

You may alter the groups this user is in:
 * A checked box means the user is in that group.
 * An unchecked box means the user is not in that group.
 * * indicates that you cannot remove the group once you have added it, or re-add the group once you have removed it.
 * General information on what each group means can be found at Help:User rights, technical details for every group can be seen here, & a list of custom-made pages for common groups can be located here.