The collection of active and passive components that allow a process to serve its purpose is the Control System. In its broadest sense, a control system exists in every non-static assembly, and separate ones can be composed of items in components or groups of components in a control system.

A fluid process involves a control system when a parameter must be controlled. A complex control system is involved in introducing fuel to an aircraft engine, as it must process many inputs in order for the engine to produce the output parameter, which is the precise amount of thrust the pilot requires. A simple system maintains pressure in a stove-top pressure cooker. To understand the workings of a control system, read on about the pressure cooker and imagine the number of components in a jet engine system