Chapter 2 – Testing Throughout the SDLC
Functional Testing – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
Testing performed to evaluate whether a component or system satisfies functional requirements.
In simple words
Does the feature do what the spec says? Login logs you in, checkout charges the right amount.
Exam tip
Functional testing answers ‘what’ the system does; non-functional testing answers ‘how well’.
Related terms
- Non-Functional TestingHow fast, how secure, how usable, how reliable — the ‘qualities’ around the feature, not the feature itself.
- Black-Box TestingYou design tests only from the spec or behaviour — inputs and expected outputs — without looking at the code.
- Test CaseA single, executable check with a clear setup, action, and expected outcome — the atomic unit of testing.
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