Global (Group) vs Category Permissions

Global permissions set what a member of a group can do in general, i.e. globally. Category permissions over-ride Global permissions. a

Here's a simple example where two people are both members of the Registered group, and one of them is also in the Chapter Canada group. Both people attempt to view the Canada Chapter forum, which has a Category called Chapter Canada.

Now, as Registered users, neither of them could see or post to any forums at all as the global group does not have the permission to view forums. But, watch what the Category does.

Note that the same objective could be achieved by using the Object permissions directly. However, this would mean every single Canada-related forum would have to have individual permissions set.

By using the Category, we only have to set the perms once, then just give any forum the category to have the standard Canada permissions apply.

Also note that a Category can carry specific permissions for everything, not just for forums. So we also define permissions regarding blogs, wiki pages, calendars, etc. for the category. Then ANY object (wiki page, calendar, blog etc.) can be given the category and the applicable part of that category's permissions will apply to that object.