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Waterfall (Traditional)

  • sequential design process, rigid and linear
  • progress is seen as flowing steadily downwards
  • phases of conception, initiation, analysis, design, construction, testing, production/implementation and maintenance.
  • Royce's phases: requirements, analysis, design, coding, testing, operations
  • one should move to a phase only when its preceding phase is reviewed and verified, and there is no turning back
  • places emphasis on documentation (such as requirements documents and design documents)
  • inflexible and costly (a bug found in later phases of development costs more)


  • It is argued that the waterfall model can be suited to projects where requirements and scope are fixed, the product itself is firm and stable, and the technology is clearly understood.[12]
  • Project requirements can be stated unambiguously and comprehensively.
  • Team members are inexperienced.
When not: