1. Quick Answer
Although Severity and Priority are closely related, they measure different aspects of a software defect.
- Severity describes how much a defect affects the functionality of the application.
- Priority describes how quickly a defect should be fixed from the business perspective.
In simple terms:
- Severity = Functional Impact
- Priority = Business Urgency
Severity focuses on how seriously the application is affected, while Priority determines the order in which defects should be resolved.
2. Comparison at a Glance
| Aspect | Severity | Priority |
| Concerned With | Application functionality | Business impact |
| Primary Question | How much does the defect affect the application? | How quickly should the defect be fixed? |
| Levels | Blocker, Critical, Major, Minor | Urgent, High, Medium, Low |
| Typically Decided By | Tester | Developer |
| Driven By | Technical impact | Business value and customer impact |
3. Severity Levels
Severity measures the technical impact of a defect on the application.
Blocker
- Testing cannot continue.
- The next module cannot be tested.
- The test engineer is unable to proceed.
Critical
- The application's primary functionality is not working.
- The tester cannot continue testing the affected feature.
Major
- Supporting functionality is affected.
- Testing can continue, although some features are impacted.
Minor
- UI or cosmetic issues are present.
- Application functionality is not significantly affected.
- Testing continues without interruption.
4. Priority Levels
Priority determines the order in which defects should be fixed.
Urgent
Requires immediate attention because of significant business impact.
High
The defect has a major impact on customers or business operations and should be fixed as soon as possible.
Medium
The defect should be resolved before the current release is completed.
Low
The defect can be postponed and addressed in a future release if necessary.
5. All Four Combinations (With Examples)
Understanding these combinations is important because interviewers often ask them to verify that Severity and Priority are independent concepts.
High Severity + Low Priority
Example:
The Privacy Notice hyperlink on the Amazon homepage does not open.
- Functionality is broken (High Severity).
- Very few users access the Privacy Notice (Low Priority).
High Severity + High Priority
Example:
A customer adds products to the cart, proceeds to checkout, completes payment, and the application crashes.
Other examples include:
- Checkout process fails.
- Shopping cart items disappear before payment.
- Login button does not work.
These issues directly affect the core business functionality, making them both High Severity and High Priority.
Low Severity + High Priority
Example:
The Amazon logo displays as "amazn.com" instead of "amazon.com".
Other examples include:
- Misspelled Flipkart logo
- Company branding mistakes
- Error on the "About Us" page
These issues do not break application functionality (Low Severity) but can significantly affect customer trust and business reputation (High Priority).
Low Severity + Low Priority
Example:
The Conditions of Use page contains a spelling mistake or alignment issue.
Other examples include:
- Spelling mistakes on rarely visited pages
- Minor UI alignment problems
- Text color not matching the application theme
These issues have minimal functional impact and low business urgency.
6. Who Decides Each?
Typically:
- Severity is determined by the Tester, who evaluates the technical and functional impact of the defect.
- Priority is determined by the Developer, considering the business urgency and release requirements.
For complete coverage of defect management, defect life cycle, triage, and bug reporting, refer to the Complete Manual Testing Guide.
Frequently Asked Questions
What is the difference between Severity and Priority?
Severity measures how much a defect affects the application's functionality.
Priority determines how quickly the defect should be fixed based on business requirements.
Can you give an example of High Severity and Low Priority?
A broken Privacy Notice link.
Although the functionality does not work (High Severity), relatively few users access this page, making it Low Priority.
Can you give an example of Low Severity and High Priority?
A misspelled company logo such as "amazn.com".
Application functionality is unaffected (Low Severity), but the company's brand image is impacted (High Priority).
Who decides Severity and Priority?
Typically:
- Severity is decided by the Tester.
- Priority is decided by the Developer based on business urgency.
What are the Severity levels?
The common Severity levels are:
- Blocker
- Critical
- Major
- Minor
These range from complete application failure to minor cosmetic issues.