Defect
A defect is a flaw in a work product that may cause a component or system to fail to perform its intended function.
“An imperfection or deficiency in a work product where it does not meet its requirements or specifications or impairs its intended use.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Defect?
Defects can originate in requirements, design, code, documentation, or test artifacts. When executed, some defects result in observable failures.
Origin: Defects can be introduced at any stage of development.
Failure relationship: Not every defect immediately causes a failure.
Detection: Defects are identified through reviews, testing, or operational use.
Real World Example
A hospital medication system shows a different dosage warning in test than the one specified by the clinical safety rule.
The team needs precise language to separate what was observed, what should have happened, and whether the difference represents a reportable issue. Defect provides that distinction.
The tester records the steps, data, observed behavior, expected behavior, and evidence so triage can focus on patient safety impact instead of vague descriptions.
The issue is handled faster because Defect helps everyone discuss the problem using a shared testing vocabulary.
Practice Questions
Question 1
Which statement BEST describes Defect in the context of ISTQB terminology?
Question 2
A tester needs to explain Defect to a non‑technical stakeholder. Which approach is MOST appropriate?
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