A system can be defined in several ways, including: (1) a set of interrelated parts that function as a whole to achieve a common purpose; (2) a piece of software that operates to manage a related collection of tasks; or (3) a design for an organization that perceives sets of processes as a related collection of tasks.

Systems can be open or closed. An open system is one that interacts with the external environment; a closed system has no external interactions. A system is normally thought to have inputs, outputs, and a transformation process by which the inputs are transformed to the desired outputs. The majority of systems are open, requiring interaction with the environment for the source of inputs and the destination for outputs.

Almost any collection of related items or tasks that take inputs and produce outputs can be characterized as a system. This also allows for...