Component

A component is a part of a system that provides a defined function and can be combined with other parts to form a complete, functioning whole. A component has a well-defined interface that specifies how other parts of the system interact with it, and it typically hides its internal implementation. The concept emphasizes modularity, interchangeability, and abstraction, allowing complex systems to be built from smaller, manageable pieces.

In software engineering, components are self-contained units that can be composed to build applications. They may be libraries, modules, frameworks, services, or plugins. Components expose APIs and have clear dependencies and versioning. They can be distributed locally as code libraries or remotely as services and microservices. The component approach supports modularity, reusability, maintainability, and parallel development, as well as easier testing and replacement of parts without affecting the whole system.

In electronics and hardware design, a component refers to a discrete electrical or electronic device such as a resistor, capacitor, transistor, inductor, diode, or an integrated circuit. In circuit diagrams, components are represented by symbols and connected on a printed circuit board or breadboard. Hardware components have specifications like ratings, tolerances, and form factors, and they interact through standardized interfaces and interconnections.

Designing with components often aims for loose coupling and high cohesion, with clearly defined contracts and interfaces. Standards and tooling in software (such as packaging, dependency management, and interface specifications) and hardware (such as form factors and connector standards) support interoperability, versioning, and scalable integration across systems.