A group of interacting or interrelated entities (called components) that form a unified whole which is:

delineated by its spatial and temporal boundaries
described by its structure and interactions between components
described by its functioning during the evolution or in response to external influence

Description of a System behaviour in response to or correlation with its properties is provided by a System Model.

Depending on whether a System has properties changing over time it can be a Static System or Dynamic System.

See also