Severity and Priority – What is the Difference?

Severity and Priority

severity-vs-priority-testing
severity-vs-priority-testing

Both Severity and Priority are attributes of a defect and should be provided in the bug report. This information is used to determine how quickly a bug should be fixed.

Severity of a defect is related to how severe a bug is. Usually the severity is defined in terms of financial loss, damage to environment, company’s reputation and loss of life.

Priority of a defect is related to how quickly a bug should be fixed and deployed to live servers. When a defect is of high severity, most likely it will also have a high priority. Likewise, a low severity defect will normally have a low priority as well.

Although it is recommended to provide both Severity and Priority when submitting a defect report, many companies will use just one, normally priority.

In the bug report, Severity and Priority are normally filled in by the person writing the bug report, but should be reviewed by the whole team.

High Severity – High Priority bug

This is when major path through the application is broken, for example, on an eCommerce website, every customers get error message on the booking form and cannot place orders, or the product page throws a Error 500 response.

High Severity – Low Priority bug

This happens when the bug causes major problems, but it only happens in very rare conditions or situations, for example, customers who use very old browsers cannot continue with their purchase of a product. Because the number of customers with very old browsers is very low, it is not a high priority to fix the issue.

High Priority – Low Severity bug

This could happen when, for example, the logo or name of the company is not displayed on the website. It is important to fix the issue as soon as possible, although it may not cause a lot of damage.

Low Priority – Low Severity bug

For cases where the bug doesn’t cause disaster and only affects very small number of customers, both Severity and Priority are assigned low, for example, the privacy policy page take a long time to load. Not many people view the privacy policy page and slow loading doesn’t affect the customers much.

The above are just examples. It is the team who should decide the Severity and Priority for each bug.

More information on Software Defects

8 Replies to “Severity and Priority – What is the Difference?”

  1. Severity is the impact of the bug in the application , In My opinion The Priority of the bug is Decided upon the Severity of the bug ..

    Priority is depend upon the severity of the bug ..
    severity and priority depends upon the risk factor of application and vary from application to application and organization process

  2. Although these two terms have been used to describe defects since the beginning of software development and testing, there are still many discussions on how to set these two defect terms.

    I have been in the testing field for over 20 years, using many different testing tools and in many different organizations both public and private from which I have developed a way to define these fields based on the test phase that has been very affective and that both business and development teams can agree with.

    Severity:
    • Severity is set based on the technical aspect of the failure during all test phases.

    Priority:
    • During SIT – set to indicate the fix order of the defects, when there are multiple defects for any given severity level.
    • During UAT – set based on the business requirement.
    • Combined SIT/UAT – set based on QA and Business agreement.

    Development Fixed and Delivered
    • During SIT the development team will fix defects based on severity and then priority.
    • During UAT or combined SIT & UAT the development team will fix defects based on Priority.

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