In software testing terminology, which attribute describes how severely a bug affects the functionality and behaviour of the application?

Introduction / Context:
In software testing and defect management, bugs are often classified using several attributes to help teams decide how to respond. Two commonly discussed attributes are severity and priority. Many interview questions ask you to distinguish between them and to identify which one refers specifically to the impact on application functionality. This question focuses on that distinction.

Given Data / Assumptions:

• A bug tracking system is used to log defects.
• Each bug record may include both severity and priority fields.
• The question asks which attribute describes how much the bug affects the application's behaviour and correctness.

Concept / Approach:
Severity measures the technical impact of a defect on the system. A high severity bug may cause crashes, data corruption or major feature failures. Lower severity issues might involve minor display problems or cosmetic glitches. Priority, on the other hand, indicates the order in which the bug should be fixed from a business or scheduling standpoint. A severe bug usually has high priority, but sometimes a less severe bug may be prioritised because it affects an important customer demo. Therefore, the attribute that directly describes how much the bug affects functionality is severity.

Step-by-Step Solution:
Step 1: Recall that severity is about impact on functionality, stability and data integrity.Step 2: Recall that priority is about when the bug should be fixed in relation to other tasks.Step 3: Option A, severity, matches the definition asked in the question.Step 4: Option B, priority, is related but deals with scheduling rather than technical impact.Step 5: Options C and D (complexity and documentation) are not standard attributes used to measure the effect of a bug on application behaviour, so option A is correct.

Verification / Alternative check:
Testing standards and QA training materials consistently define severity as the degree of impact that a defect has on the development or operation of a component or system. Examples classify bugs as critical, major, minor or trivial based on severity. Priority is defined separately as the level of urgency to fix the defect, often controlled by project managers or product owners. These definitions confirm that severity is the attribute that directly answers the question.

Why Other Options Are Wrong:
Option B, priority, does not describe the inherent impact of the bug; it describes scheduling decisions that may be influenced by business context. Option C, complexity, might refer to the difficulty of fixing the bug but not necessarily the effect on users. Option D, documentation, is an artefact that may describe the bug, not an attribute that measures its effect.

Common Pitfalls:
Testers new to the field sometimes use severity and priority interchangeably, which can cause confusion in planning. Another mistake is to assign high priority to every bug, ignoring the severity classification. When answering exam or interview questions, clearly state that severity is about how badly the bug breaks functionality, whereas priority is about how soon the team should address it.

Final Answer:
Severity