Conway's law is an adage named after computer programmer Melvin Conway, who introduced the idea in 1967; it was first dubbed Conway's law by participants at the 1968 National Symposium on Modular Programming. It states that
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organizations which design systems ... are constrained to produce designs which are copies of the communication structures of these organizations
The law is based on the reasoning that in order for a software module to function, multiple authors must communicate frequently with each other. Therefore, the software interface structure of a system will reflect the social boundaries of the organization(s) that produced it, across which communication is more difficult. Conway's law was intended as a valid sociological observation, although sometimes it's taken in a humorous context.
Variations
Eric S Raymond, an open source advocate, restated Conway's law in The New Hacker's Dictionary, a reference work based on the Jargon File. The organization of the software and the organization of the software team will be congruent, he said. Summarizing an example in Conway's paper, Raymond wrote that "If you have four groups working on a compiler, you'll get a 4-pass compiler".
James O. Coplien and Neil B. Harrison stated that "If the parts of an organization (e.g. teams, departments, or subdivisions) do not closely reflect the essential parts of the product, or if the relationship between organizations do not reflect the relationships between product parts, then the project will be in trouble... Therefore: Make sure the organization is compatible with the product architecture".
The impact of Conway's Law can be seen in the design of corporate websites. Nigel Bevan, a usability expert, states that "Organisations often produce web sites with a content and structure which mirrors the internal concerns of the organisation rather than the needs of the users of the site." A similar effect may be found when websites undergo design by committee.
Supporting evidence
Evidence in support of Conway's law has been published by a team of MIT and Harvard Business School researchers, who found "strong evidence to support [what they term the equivalent]… mirroring hypothesis", and that "significant differences in [product] modularity" were "consistent with a view that distributed teams tend to develop more modular products".
Additional and likewise supportive case studies of Conway's law have been conducted by Nagappan, Murphy and Basili at the University of Maryland in collaboration with Microsoft, and by Syeed and Hammouda at Tampere University of Technology, in Finland.