Functional Testing
Functional testing verifies that software functions according to specified requirements by validating inputs, outputs, and business behavior.
“Testing performed to evaluate if a component or system satisfies functional requirements.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Functional Testing?
Functional testing focuses on what the software does rather than how it is implemented, ensuring each feature behaves as expected.
Requirement-based: Test cases are derived from functional specifications.
Black-box approach: Internal implementation details are not considered.
Business validation: Confirms that user and business requirements are satisfied.
Real World Example
A regulated product team is preparing a release where Functional testing appears in reviews, test design conversations, or defect triage rather than as an isolated glossary word.
The risk is that the team treats Functional testing as interchangeable with nearby ISTQB terms. That makes test scope blurry and can lead to weak evidence for the release decision.
The tester anchors the discussion in the official definition, asks where the concept appears in the product, and designs examples that show the difference between Functional testing and similar ideas.
The page becomes useful in practice because Functional testing is connected to a specific testing decision, not memorized as a detached definition.
Practice Questions
Question 1
Which statement BEST describes Functional testing in the context of ISTQB terminology?
Question 2
A tester needs to explain Functional testing to a non‑technical stakeholder. Which approach is MOST appropriate?
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