Access to various parts of your forum is controlled by a rich and flexible permissions system. The basic unit which controls permissions is a user group. As you would expect, a user group is really just a group of any number of users.

Through this, you may control what this group of users is allowed to do on your forum.

For example, perhaps you want only administrators to be able to post in a specific category? Or only certain users to be able to attach files with their posts? Or maybe even allow a group of users to have their own user titles? These are all possible with user group permissions.

A user can belong to multiple user groups. The permissions from a user's additional user groups merge together in determining their final permissions, such that one Yes permission overrides all other No permissions. For example, if a user is a member of 3 user groups and the Post Topics permission looks like this among all of the groups:

Group 1 - No
Group 2 - No
Group 3 - Yes

...then the overall Post Topics permission for that user will be Yes, because one Yes overrides any number of No's.