Waterfall is a traditional software development methodology that follows a linear and sequential approach, akin to a cascading waterfall. Each phase—such as requirements gathering, design, implementation, testing, and maintenance—must be completed before the next one begins. This method is useful in projects where requirements are well-understood and unlikely to change, as it emphasizes thorough documentation and a clear project roadmap.
Despite its structured approach, Waterfall is placed in the "hold" ring because contemporary software development often demands flexibility to accommodate changing requirements and iterative improvements, which are better supported by agile methodologies. In the "methods-and-patterns" quadrant, Waterfall serves as a historical reference point that helps understand the evolution of software development practices. It remains relevant for certain industries like aerospace and construction, where rigorous adherence to specifications is critical.