modular

Modular is an adjective used to describe systems, components, or approaches built from smaller, interchangeable parts, or modules. A modular design organizes complex systems into discrete units with standardized interfaces, enabling assembly, reconfiguration, upgrade, or replacement without affecting the whole.

In mathematics, modular refers to structures defined with respect to a modulus. The most familiar is modular arithmetic, which deals with integers modulo n and operations that wrap around at n. More advanced, modular forms are complex analytic functions with symmetry properties under a modular group and have important roles in number theory and geometry.

Engineering and architecture commonly use modular construction, which relies on prefabricated modules produced off-site and assembled on-site. This approach can improve speed, quality control, and logistics, while allowing scalable configurations.

In software and systems, modular programming designs software as a collection of independent modules with well-defined interfaces. This supports maintainability, testability, and reuse, and aligns with architectures such as modular monoliths and microservices.

Modular concepts also appear in consumer products and furniture, electronics, and storage systems, where standard components can be combined in multiple configurations.

In music and audio hardware, modular synthesis uses separate modules—oscillators, filters, envelopes—connected by patch cables to create sounds. Hardware generally follows expandable, modular form factors, enabling new functionality by adding modules.

Beyond these, modularity informs curricula design, organizational structure, and product ecosystems by emphasizing separable, interoperable units.