The most wanted feature of Joomla! 1.6 is probably the new permissions system, called Access Control List (ACL). With Joomla! 1.6 ACL, you are able to define who has permission to do what on the website, called actions, like the login, configure, access, create, delete, edit and edit state.
These permissions are given to a group of users. You can configure the group permissions on 4 levels: Global configuration, Components and, if applicable, for Categories and Items.
Joomla! ACL is a great tool to define your own groups and their permissions. Unfortunately you will probably not enjoy the new Joomla! permissions system immediately due the difficulty to understand how the system works. It can be quite abstract.
This is where the ACL Manager for Joomla! 1.6 comes in!