In defect management, what is the difference between severity and priority of a bug, and how are they used together to decide fixes?

Introduction / Context:
In software testing and defect tracking, two commonly used attributes of a bug are severity and priority. Although they are related, they describe different aspects of a defect and are used by both technical and business teams to decide which issues to fix first. Understanding this distinction is vital for testers, developers, and project managers, because it influences release planning, risk assessment, and communication with stakeholders. Interview questions often focus on correctly defining both terms and explaining how they interact in real world examples.

Given Data / Assumptions:
- The question concerns conceptual definitions, not any specific bug tracking tool.
- Severity is associated with the technical seriousness or impact of a defect on the system behaviour.
- Priority is associated with the urgency for fixing the defect from a business or project perspective.
- Examples often include high severity but low priority issues and the reverse case.

Concept / Approach:
Severity describes how badly a defect breaks the system. A high severity bug may cause a crash, data loss, or complete feature failure. A low severity defect might be a minor layout issue or a small spelling error. Priority describes how quickly the team should address the defect, considering release deadlines, business impact, and customer commitments. A cosmetic issue on the main landing page before a major release may be low severity but high priority. Therefore, the correct option must state that severity is the technical impact, while priority is the business urgency for fixing the defect.

Step-by-Step Solution:
Step 1: Recall the definition of severity as a measure of the effect of the defect on system functionality or stability.Step 2: Recall the definition of priority as the order in which defects should be fixed based on business importance and deadlines.Step 3: Consider examples: a system crash on every login is both high severity and high priority, while a spelling error on an internal page is low severity and probably low priority.Step 4: Review the options and identify which one clearly separates severity as technical impact and priority as fix urgency driven by business needs.Step 5: Select option A because it correctly captures both meanings in one sentence.

Verification / Alternative check:
Imagine a bug that corrupts financial data but occurs in a rarely used admin screen. Its severity is very high because it damages important data. However, if the screen is temporarily disabled, the priority might be adjusted based on release plans. On the other hand, consider a typo on the home page headline. Technically it is low severity, but marketing may consider it urgent to fix before a product launch, making its priority high. These scenarios confirm that severity and priority measure different dimensions and should not be confused.

Why Other Options Are Wrong:
Option B incorrectly ties severity to the age of the defect and priority to the number of lines of code, which are not standard industry definitions. Option C claims severity is assigned only by customers and priority only by database administrators, which is unrealistic; in practice, testers, developers, business analysts, and product owners collaborate on these values. Option D states that severity and priority are the same concept, which is fundamentally wrong and ignores the different purposes they serve in defect management.

Common Pitfalls:
A common misunderstanding is to think that all high severity bugs are automatically high priority or that low severity always means low priority. In reality, business context, release schedules, and customer expectations strongly influence priority. Another pitfall is inconsistent use of severity and priority scales across teams, which makes reports unclear. To avoid confusion, organisations should define clear criteria for each level of severity and priority and train team members to apply them consistently when logging and triaging defects.

Final Answer:
Correct answer: Severity measures the technical impact of the defect on the system, while priority indicates how soon the defect should be fixed based on business needs