Modularity is the degree to which a system's components may be separated and recombined. The meaning of the word, however, can vary somewhat by context:

• In biology, modularity is the concept that organisms or metabolic pathways are composed of modules.
• In construction, modules are a bundle of redundant project components that are produced en masse prior to installation.
• In nature, modularity refers to the construction of a cellular organism by joining together standardized units to form larger compositions, as for example, the hexagonal cells in a honeycomb.
• In the Five Principles of New Media as defined by Lev Manovich, modularity covers the principle that new media is composed of modules or self-sufficient parts of the overall media object.
• In the study of networks, modularity (networks) is a benefit function that measures the quality of a division of a network into groups or communities.
• In ecology, modularity is considered a key factor – along with diversity and feedback – in supporting resilience.
• In mathematics, the term can be used in several different ways. A module over a ring is a generalization of the notion of vector space over a field. Modular lattices are partially ordered sets which generalize the order structure of submodules. The modularity theorem (formerly the Taniyama–Shimura conjecture) establishes a connection between elliptic curves and modular forms.
• In cognitive science, the idea of modularity of mind holds that the mind is composed of independent, closed, domain-specific processing modules.
  • Specifically, see visual modularity, for an article relating to the various putative visual modules.
  • Specifically, see language module, for an article relating to the putative language module.
• In industrial design, modularity refers to an engineering technique that builds larger systems by combining smaller subsystems.
• In manufacturing, modularity refers to the use of exchangeable parts or options in the fabrication of an object.
• In modular programming, modularity refers to the compartmentalization and inter-relation of the parts of a software package.
• In contemporary art and architecture, modularity can refer to the construction of an object by joining together standardized units to form larger compositions, and/or to the use of a module as a standardized unit of measurement and proportion.
• In ModulArt – a branch of modular art – modularity refers to the ability to alter the work by reconfiguring, adding to and/or removing its parts.
• In software design, modularity refers to a logical partitioning of the "software design" that allows complex software to be manageable for the purpose of implementation and maintenance. The logic of partitioning may be based on related functions, implementation considerations, data links, or other criteria.
• In self-reconfiguring modular robot, modularity refers to the ability of the robotic system to automatically achieve different morphologies to execute the task at hand.