Zotonic has a pluggable access control system. The default module is the ACL User Groups module, which works together with the Content Groups module. With these modules every resource (page) is placed in a single content group. Users are assigned to user groups, and rules are defined which user group can do what (edit, delete, link, create) on resources in a content group.<\/p>\n
This is a very robust system for editorial work and sites with individual users. These sites have typically a set of rules for members, and an extended set of rules for editors or administrators.<\/p>\n
It is different if we want to organize the users into smaller groups, like classes in a school. With the above system we would need to a user group and a content group for each class. And then also a set of rules for every combination of user group and content group.<\/p>\n
This gets complicated very quickly and is not workable for any system with more than a couple classes (user groups).<\/p>\n
That is why collaboration groups were added. Collaboration groups are a combination of user groups and content groups. They behave as content groups as all the resources of the collaboration group are placed in the collaboration group (and not one of the standard content groups). They also behave as user groups as users can be member of collaboration groups.<\/p>\n