For a manufacturing system to achieve its maximum performance, the operations of its subsystem, including machines and personnel, as well as the flow of parts and products, should be well coordinated; this requires proper scheduling of the operations and flows. For example, if many parts are waiting to be processed by a certain machine, a decision must be made as to which part should be processed next when the machine finishes the current processing (job dispatching problem).

When there are several machines capable of performing the same job, a machine must be selected for the task (machine selection problem). For a longer time scale, it is necessary to schedule when and how many of each product should be produced. The results of these decisions must satisfy certain production requirements. For example, the total time required to produce a certain number of products; the production delay from the due date (the time when each product should be completed); and the cost required for the personnel, machines, or inventory ideally should be minimized.

In the recent trend for designing more flexible manufacturing systems, more and more decision-making points are introduced in order to deal with the demands for producing a large variety of products in small amounts and in frequently changing environments, where the proper scheduling plays an even more essential role.