Waterfall Model

Updated 06 Sep 2026

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def
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  a plan-driven Software Process Models with separate, distinct, sequential phases
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  each phase must be completed before the next one begins
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phases
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  requirements analysis and definition
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  system and software design
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  implementation and unit testing
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  integration and system testing
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  operation and maintenance
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advantages
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  clear documentation at each phase
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  easy to manage due to its rigid structure — each phase has specific deliverables
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  works well when requirements are well-understood and unlikely to change
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  suitable for large-scale engineering projects developed at multiple sites
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disadvantages
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  inflexible — difficult to accommodate changing requirements once a phase is complete
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  customer sees the working product only late in the process
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  few business systems have truly stable requirements
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when to use
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  requirements are well-understood and stable
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  part of a large system engineering project
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  projects where multiple teams must coordinate at different sites
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Distinguish from
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  Spiral Model — adds explicit risk analysis per iteration
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  V-Model — pairs each phase with a specific testing phase
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  Rapid Application Development (RAD) — trades planning for fast prototyping
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  Rational Unified Process (RUP) — iterative, object-oriented, phase-based (inception/elaboration/construction/transition)
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related
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Cards
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  What's the key tradeoff between Waterfall and Agile?
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    Waterfall: sequential, needs stable requirements, heavy documentation, low flexibility; Agile: iterative, embraces changing requirements, high flexibility, lighter documentation

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Waterfall Model

Distinguish from

Cards

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