One of the biggest recent changes in Joomla is the introduction of a new system to manage user permissions, and it is usually referred to as Access Control List (ACL). Currently, Joomla offers you almost infinite control of what users can see and do on the site. However, out of the box, the ACL system already comes with a set of basic user groups and default permissions—and in many cases, these may offer all the features you need. We'll first have a look at the basics; later in this chapter, we'll cover an example of more advanced ways to deploy the ACL system by crafting made-to-measure user groups and their distinctive permission settings.