1) It refers to the manner in which customers behave in a queue, and to the order in which they are served up. For illustration; A customer may arrive at a queue and decide that it is too long and go away;
2) The queue may be at a maximum length so that a new customer arriving cannot join it.
3) A customer may be kept waiting so long in the queue that he/she decides to leave it.
4) In a complex channel system, a customer may cross over from one queue to another because it seems shorter.
5) A steady state or a transient state – customers may be served in several ways depending on either the server or the customers;
Customer may be given priority treatment:
1) An official may deal with his in-tray by taking the top documents out first i.e. LIFO system.
2) There may be a first come first served queue discipline i.e. FIFO.
3) A queue or a service system is in a transitory state whenever it is dependent on time. (e.g. workers canteen may be kept open all day, but there will be times of the day when the system is busy and times when it is relatively empty.
4) A system is in a stable state or in equilibrium whenever it is not dependent on time. Steady state systems are the ones commonly considered in queuing theory.
5) A system may be in a transient state for a short time (e.g. when a service counter opens there might be an initial rush of customers) but then it may settle down into a steady state (until it closes for the day.)