A queue is a holding area for records before they are processed by a member of the group . Records remain in a queue until a user takes the record’s ownership or the record is transferred to another queue. You can specify the object(s) to include in each queue, as well as queue members allowed to retrieve and own records from the queue.
They are used in the assignment rules and represent ownership (a queue may be the owner of a record).
Each user can view in his personal settings what queues he has been assigned to.