Defect Taxonomy
A defect taxonomy is a structured classification system used to categorize defects based on their characteristics, causes, or impact.
“A list of categories designed to identify and classify defects.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Defect Taxonomy?
Defect taxonomies help organizations analyze defect trends, identify recurring problems, and improve development and testing processes.
Classification: Defects are grouped into meaningful categories such as functional, performance, usability, or security.
Trend analysis: Categories help identify recurring quality problems.
Process improvement: Taxonomies support root cause analysis and defect prevention.
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 taxonomy 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 taxonomy helps everyone discuss the problem using a shared testing vocabulary.
Practice Questions
Question 1
Which statement BEST describes Defect taxonomy in the context of ISTQB terminology?
Question 2
A tester needs to explain Defect taxonomy to a non‑technical stakeholder. Which approach is MOST appropriate?
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