systems

A system is a set of interrelated components that collectively perform a function or achieve a purpose. Systems are often bounded by a defined boundary and interact with their environment through inputs and outputs. The study of systems emphasizes how parts connect and how the behavior of the whole arises from their interactions.

Systems can be categorized by openness, dynamics, and organization. Open systems exchange energy, matter, or information with their surroundings; closed systems minimize such exchanges. Many systems are dynamic and adapt over time, showing changes in state, structure, or behavior. Subsystems, modules, or components form hierarchical structures, and a system can contain other systems, creating a layered architecture often described as a system of systems.

Key concepts in system analysis include feedback and control, stability, and emergence. Feedback loops monitor outcomes and adjust inputs to regulate behavior; emergence refers to properties and behaviors that arise from interactions among parts and are not present in any single component.

Examples span natural and engineered domains. Natural systems include biological organisms and ecosystems; engineered systems cover computer networks, software architectures, transportation, and manufacturing. In practice, systems theory informs systems engineering, which aims to understand requirements, design components, integrate them, and ensure performance over the life of a project. Modeling and analysis methods such as systems dynamics, network theory, and control theory are used to study behavior, optimize performance, and manage complexity and uncertainty.