Waterfall model

The Waterfall model is a software development model first proposed in 1970 by W. W. Royce[?], in which development proceeds linearly through the phases of requirements analysis[?], design, implementation[?], testing (validation), integration and maintenance.

In practice, the process rarely proceeds in a purely linear fashion. Iterations, by going back to or adapting results of the precedent stage, are common.

The Waterfall model is considered old-fashioned or simplistic by proponents of object-oriented design[?] which often uses the spiral model instead.

See also: Project lifecycle.

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This article (or an earlier version of it) contains material from FOLDOC's article on Waterfall Model, used with permission.