Severity vs. Priority in Software Testing

Severity

Error severity or defect severity in testing is the degree of impact of the defect or defect on the application being tested. A higher impact of the error/failure on the functionality of the system results in a higher severity level. The quality assurance engineer usually determines the severity of the defect/failure.

Priority

Priority is defined as the order in which faults are fixed. The higher the priority, the faster the error should be fixed. Defects that render a software system unusable are more serious than errors that cause minor software malfunctions.

Difference between Severity and Priority

#	Priority	Severity
1	Defect Priority has defined the order in which the developer should resolve a defect	Defect Severity is defined as the degree of impact that a defect has on the operation of the product
2	Priority is categorized into three types. Low, Medium and High	Severity is categorized into five types. Critical, Major, Moderate, Minor and Cosmetic
3	Priority is associated with scheduling	Severity is associated with functionality or standards
4	Priority indicates how soon the bug should be fixed	Severity indicates the seriousness of the defect in the product functionality
5	Priority of defects is decided in consultation with the manager/client	QA engineer determines the severity level of the defect
6	Priority is driven by business value	Severity is driven by functionality
7	Its value is subjective and can change over some time depending on the change in the project situation	Its value is objective and less likely to change
8	High priority and low severity status indicates, the defect has to be fixed on immediate bases but does not affect the application	High severity and low priority status indicate defect has to be fixed but not on immediate bases
9	Priority status is based on customer requirements	Severity status is based on the technical aspect of the product
10	During UAT the development team fixes defects based on priority	During SIT, the development team will fix defects based on the severity and then the priority

A real-life example of Severity and Priority

Let's take an example of two patients reached a doctor at the same time:

Patient A: He is suffering from a cold.

Patient B: He is suffering from chest pain.

Now the doctor needs to decide on whom he should attend first. Based on the issue both patients are facing doctor will first diagnose Patient B as the issue with him is of high severity and the priority of Patient B will become high.

Example of Severity and Priority

1	A very low severity with a high priority	A front-facing webpage is not showing the company logo.
2	A very high severity with a high priority	A customer order a Web Camera but in the backend two duplicate orders are created and sent to the delivery center for processing.
3	A very low severity with a low priority	A typo on a webpage that is not front facing to customer.
4	A very high severity with a low priority	An admin page that is showing server error but is not a very commonly used feature by all admins.