Groups are collections of users. A group can be used to successfully manage a large number of users. Administrators are allowed to create groups in Confluence and add users to these groups. Permissions are then assigned to groups instead of users to allow easier management.
There are two default groups already available in Confluence, and these are special groups:
confluence-administrators: This group represents the "super users". The members of this group can access the Administration Console and perform side-wide administrative actions, such as installing plugins or changing the security of your site.