Queuing refers to the act of waiting in a line of people, vehicles, or things, often to buy something or receive a service. It is a common phenomenon in everyday life, and it can also be studied mathematically as a branch of operations research known as queuing theory. Queuing theory is the study of the movement of people, objects, or information through a line, covering all aspects from arrival time to the number of servers. It is used to identify and correct points of congestion in a process, and it can help inform business decisions on how to build more efficient and cost-effective workflow systems. Queuing theory is often used by Six Sigma practitioners to improve processes, and it can be used to determine and streamline staffing needs, scheduling, and inventory in order to improve overall customer service.