A queueing system can be described as the flow of items through a queue. In a queueing system, items arrive at some rate to the system and join one or more queues inside the system. These items receive some kind of service, and when the work is done, they depart the system. A simple queueing system Little’s Law is a pretty simple model of queueing systems. $$ L=\lambda W $$ Little’s Law says that the average number of items in a queueing system, denoted \(L\), equals the average arrival rate of items in the system, \(\lambda\), multiplied by the average waiting time of an item in the system, \(W\).