Updated July 1, 2023

Difference Between Severity and Priority

While learning the concepts of Software Engineering, we all have come across the two words ‘Severity’ vs ‘Priority’ and always faced confusion between them. If we ask any non-technical person, the difference between them is nothing. For him, both have the same meaning. But technically, as per the Software Engineer, the above two are different words having different meanings and are used in a different contexts. Let’s understand them one by one.

Severity

During Test Execution, when the tester finds the defect and logs it in any Defect Logging tool like JIRA, Testrail, etc., to submit for the developers to work on, a tester needs to decide the Priority and Severity based on the defect criticality and complexity so that a developer can deal accordingly. In layman terms, Severity is defined as the ‘degree of impact that anything can have. So Severity in terms of Defect indicates to what degree a particular defect has an impact on the Software/application. It means to what extent a defect can affect an application. Usually, Severity is defined in terms of financial loss, reputation, and loss of life, depending on the application.

Severity is categorized in different categories depending on the impact of the defect on the application:

Critical: A defect that hampers the entire application and blocks the user from proceeding or using the application because it is considered critical. Considering the UI of the application, if the Login Screen of the application hangs and does not allow the user to log in and proceed further.
Major: A defect is considered major if the Major/ important feature of an application is not working as expected or intended to perform. If any significant feature implemented in an application is working completely differently from it’s expected behavior, then the defect for this will be considered as Major. For example, while doing Online shopping, the user is unable to add products to the cart using Add to Cart feature.
Minor/Moderate: Any feature that is implemented and working differently from the expected behavior but its impacts are tolerable and would not harm the application too much, and the overall functionality of the application is not affected. A minor defect can wait to be resolved for some time, or it can be tackled in the next release of the application. For example, on the Terms and Condition page, one of the links is not working.
Low: Any defect that does not harm the functionality but is a valid defect and needs to be corrected. Cosmetic bugs like spelling mistakes and slight misalignment of fonts fall into this category. A few spelling mistakes on a web page are an example of a Low Severity defect.

Priority

Priority in simple English is used in the comparison of two things and where importance is given to one of them. Similarly, in terms of Defects, Priority is the urgency of the defect to be fixed. It refers to the order in which defects need to be fixed, keeping in mind their severity and business needs.

Developers cannot fix so many defects simultaneously, so it is important to prioritize the order of the defects they will fix. Usually, High Severity defects are of High Priority as they demand quick fixing. The priority of defects is categorized as follows:

High: Any defect that needs immediate attention and needs to be fixed as soon as possible (max 24 hours). Defects that largely impact the end customers and business come under this category. When the entire application is blocked, testers cannot proceed with further software testing due to these high-priority issues.
Medium: Defects that can wait to get fixed as they are not affecting the application’s major functionality and do not hamper the business and customer falls in this category.
Low: Defects filed for changes in the existing design to enhance the customer experience are considered Low priority defects. These defects need less attention, and hence they are considered at last when all the other priority defects have been fixed.

Severity vs. Priority Infographics

Below are the top 6 differences between Severity and Priority:

Key Differences between Severity vs. Priority

Below are the lists of points, that describe the key differences between Severity vs Priority:

The severity of a defect decides the impact on the application, whereas Priority decides the order in which defects need to be fixed.
Severity deals with the technical aspects of an application, whereas Priority deals with Business Requirements and the impact of the defect on customer requirements.
The severity of any defect does not change as the impact of it remains the same on the application, whereas Priority changes if the business requirements change or any defect of more Priority is encountered, which needs more attention.

Understanding the Differences between – Example

Below are the points, that help to understand the difference between Severity vs Priority:

High Priority and High Severity

In an application, if there is an issue with the login screen and the user is not able to log in, then that defect falls in High Priority, and High Severity, as this needs to be resolved first because the user is blocked and cannot access the application further.

High Priority and Low Severity

If there are some spelling mistakes on the Home page of the application or any other web page which is used frequently is an example of High Priority, and Low Severity as Spelling mistakes are not hampering the functionality of the application but make a bad impact on a company’s reputation.

Low Priority and High Severity

In an Online Shopping website, if the ‘Add to Cart’ button stops working if the user tries to add more than 500 items to a cart, then the defect is considered as High Severity as the major functionality is not working as expected but Low Priority because it is a very rare case that user add more than 500 items in cart.

Low Priority and Low Severity

If there are some spelling mistakes in a paragraph of a page that the user rarely opens, it is considered Low Priority and Low Severity because neither it is creating an impact on the functionality of the application nor any loss to a company’s reputation it is rarely opened.

Comparative Table

Below is the topmost comparison between Severity and Priority

Sr.no.	Severity	Priority
1.	Severity is driven by the functionality or standards of an application.	Priority is driven by business value.
2.	Severity defines the degree of impact that a defect has on application.	Priority defines the order in which the defects will be fixed by the developer.
3.	Severity is decided by QA Engineer who is logging the defect.	Although the tester can decide the Priority, the final decision is taken by the Product Manager, keeping in mind the overall view of the product.
4.	The severity value is objective and less likely to change over time.	The priority value is subjective and can be changed over time, depending on other defects and project requirements.
5.	Severity is categorized as follows: Critical Major Minor/Moderate Low	Priority is categorized as follows: High Medium Low
6.	High Severity defects with Low Priority are considered later after High Priority defects are resolved.	High Priority defects are fixed first, then High Severity as they hamper the business.

Conclusion

For a Tester, it is essential to know the difference between Severity and Priority and assign them properly to a defect because even a small mistake in the assignment of Severity can cause a huge loss in an application and a company’s reputation. The wrong assignment of Priority can cause a delay in resolving a defect that needs prior attention and hence can hamper the product requirements and financial loss. As a tester, while logging a defect, it is important to drill down and understand the impact of that defect on the end-user, then assign the right Severity and Priority to a defect.

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