Glossary » waterfall model
a traditional linear model of the software development process that suggests each phase of development could be completed independently and pass its results onto the next phase. Thus, a requirements phase would produce a requirements document that would then be used as input to a system architecture phase. This traditional approach has been widely criticized and various approaches stressing a more iterative development process have been preferred. The central problem is the need for feedback from later stages in development to inform earlier stages, such as the requirements phase. This is often achieved through successively refining prototypes toward the final system and updating the requirements and design as a better understanding is developed.