2.3 Queue
A queue contains tickets generally of a similar nature, for example, a technical support queue.
Multiple queues may be set up, and each will have its own email address. So you might have one queue, noc@example.com, which is monitored by technical staff, and billing@example.com, which is used by accounts staff.
Tickets may be moved between queues, so a tech could pass a ticket onto the accounts department once work has completed.
Also, queues can be configured differently, so the noc queue may issue an autoresponse when a ticket is created, whereas the accounts queue might be configured to prevent internal correspondance being sent to the requestor.