Queueing theory is the mathematical study of waiting lines, or queues.[1] In queueing theory a model is constructed so that queue lengths and waiting times can be predicted.[1] Queueing theory is generally considered a branch of operations research because the results are often used when making business decisions about the resources needed to provide a service.
Queueing theory has its origins in research by Agner Krarup Erlang when he created models to describe the Copenhagen telephone exchange.[1] The ideas have since seen applications including telecommunication, traffic engineering, computing[2] and the design of factories, shops, offices and hospitals.[3][4]