System

A system is an interconnected set of elements forming an entity with a specific purpose or function. They have boundaries that separate them from their environment, and a behavior that arises from interactions among components rather than from any single part.

Systems can be physical or abstract. They include natural systems (ecological, geological), engineered systems (vehicles, networks), biological systems (nervous system), social systems (institutions, markets), and informational systems (computing networks). They are characterized by components, structure, processes, and outputs, with inputs from the environment and feedback that affects future behavior.

Key concepts include open vs closed systems; inputs, outputs, state, and feedback loops. Stability and resilience describe how a system responds to disturbance. Complex systems exhibit emergent properties not predictable from individual parts.

In engineering and management, systems theory and systems engineering study how to design, integrate, and manage complex systems across their lifecycles. The concept appears in many disciplines, emphasizing interdependence, boundary definitions, and the importance of interfaces.