Severity

Severity is a classification that measures the impact of a defect or bug on the functionality and performance of a software system. It is a technical metric, determined by the tester, that answers the question: "How bad is this bug?" A high-severity defect causes major functionality to fail or the system to crash, while a low-severity defect might be a simple cosmetic issue. Severity is often confused with priority, which is a business-driven metric for how quickly a bug needs to be fixed.

Severity Levels

Defects are typically classified into a few levels of severity:

• Critical: The bug causes a complete system crash or makes a major feature unusable. There is no workaround.
• High: A major function is broken, but there might be a temporary workaround.
• Medium: A minor function is not working as expected, or the bug is an annoying usability issue.
• Low: A cosmetic or minor issue that doesn't affect functionality, such as a spelling mistake or a misaligned button.

Example: A tester finds two defects on a new login page.

1. A critical defect: Clicking the "Login" button causes the application to crash completely. This would be classified as high severity because it makes the entire application unusable.
2. A low severity defect: The "Forgot Password?" link is a slightly different shade of blue than the rest of the links on the page. This would be classified as low severity because it's a minor visual inconsistency that doesn't affect the user's ability to log in.