Queuing system is described by its calling population, queue, server, entity (customers), nature of arrival, service mechanism, system capacity and queuing discipline. Entity comes from calling population and join the queue. If any of the server is idle, entity on the queue moves to the server. Otherwise, if all servers are busy, entity waits on the queue, and as soon as server state changes to ideal, entity moves to the server. After the entity is served, the entity goes back to the calling population. The time between the arrivals of each entity is known as inter arrival time. The time taken by the server to serve an entity is known as service time.