Chapter 2 – Testing Throughout the SDLC
Spiral Model – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
An iterative SDLC model that combines waterfall and prototyping with an explicit focus on risk analysis at each cycle.
In simple words
A repeating cycle of planning, risk analysis, engineering, and evaluation.
Exam tip
Boehm’s spiral is the canonical risk-driven lifecycle — expect it alongside V-model and Agile in ISTQB.
Related terms
- V-ModelEach dev phase (requirements, design, code) has a matching test level (acceptance, system, component) drawn as a V.
- Waterfall ModelRequirements → design → build → test → release, in a straight line with limited backtracking.
- Iterative Development ModelYou build the product in loops, learning and refining each time, instead of one big waterfall.
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