Joomla! Documentation™

Access Control List o ACL è, secondo la definizione di Wikipedia, “...ACL specifica a quali utenti o processi di sistema è garantito l'accesso agli oggetti, e quali operazioni sono consentite per essere effettuate in dati oggetti.” Nel caso di Joomla ci sono due aspetti separati del suo Access Control List che l'amministratore può controllare:

• Which users can gain access to what parts of the website? For example, will a given menu choice be visible for a given user? A registered user can view, but the public at large cannot. Perhaps the menu choice is hidden from all except an Editor user and higher.
• What operations (or actions) can a user perform on any given object? For example, can a user listed as an "Editor" submit an article or only edit an existing article. The ACL settings could allow submitting and editing, or allow a change an article's category, add tags or any combination.

The implementation of ACL in Joomla was substantially changed in the Joomla! 2.5 series which allowed for more flexibility in groups and permissions.