Defect Severity and Priority Explained!

All of you must be knowing about Defect Prioroty and Severity, as they are main aspect of any defect. But do you know about Priority and Severity values in any defect detection process?
Here is the explaination for Severity and Priority Values with proper examples :

Severity Value : S1 : Catastrophic Blocking :
The use case cannot be completed with any level of workaround. Problem causes data loss, corruption, or distortion. There is defective program functionality with no workaround. A system or product crash or fatal error occurs. Program produces an incorrect result, particularly when the result could cause an incorrect business decision to be made. Problem causes inability to use the product further. Problem results in considerable performance degradation, (i.e., 3+ times longer than requirement). The error will definitely cause a customer support call. A severity 1 bug would prevent the product from being released.

Severity Value : S2 :Serious (Critical/Major) :
The failure is severe and can be avoided with some level of workaround. There must be some means of completing the use case, however,the workaround is undesirable.. Program does not function according to product or design specifications. Product produces data or results that are misleading to the user. Problem results in performance degradation that is less than required (i.e., takes twice as long). There is a serious inconsistency or inconvenience. Problem is likely to cause a customer support call.

Severity Value : S3 : Normal
Soft failure, the main flow of the use case works but there are behavioral or data problems. Performance may be less then desired.Problem is a of less intensity or typographical issue. There is a minor functional problem with a reasonably satisfactory workaround. Problem is a minor inconvenience. Problem is a non-intuitive or clumsy function. Problem is not likely to cause a customer support call. A defect that causes the failure of non-critical aspects of the system. . The product may be released if the defect is documented but the existence of the defect may cause customer dissatisfaction.

Severity Value : S4 : Small (Minor) :
There is no failure, the use case completes as designed. Fix would slightly improve the use case behavior or performance. A minor condition or documentation error that has no significant effect on the Customer's operations. Also: Additional requests for new features and suggestions, which are defined as new functionality in existing License Software.Generally, the product could be released and most customers would be unaware of the defect's existence of only slightly dissatisfied.Such defects do not affect the release of the product.


Priority Value : P1 :
FIX the bug ASAP


Priority Value : P2 :
Bug can be fixed before current itteration/minor release.


Priority Value : P3 :
The bug is very minor. A fix for this defect is not expected during the current itteration/minor release.

Priority Value : P4 :
This defect does not need to be addressed in the current final release.


Type Of Defect :
High Severity & Low Priority (S1/S2 & P4) :
1) An application which generates some banking related reports weekly, monthly, quarterly & yearly by doing some calculations. If there is a fault while calculating yearly report. This is a high severity fault but low priority [Exception : If this defect is discovered during last week of the year] because this fault can be fixed in the next release as a change request.2) An inability to access a rarely used menu option may be of low priority to the business, but the severity is high as a series of tests cannot be executed, all dependent on access to the option.

High Severity & High Priority (S1/S2 & P1) :
1) If there is a fault while calculating weekly report. This is a high severity and high priority fault because this fault will block the functionality of the application immediately within a week. It should be fixed urgently.

Low Severity & High Priority(S4 & P1):
1) If there is a spelling mistake or content issue on the homepage of a website which has daily hits of lakhs. In this case, though this fault is not affecting the website or other functionalities but considering the status and popularity of the website in the competitive market it is a high priority fault.
2) A spelling mistake would be deemed as a low severity by the tester, but if this mistake occurs in the company name or address, this would be classed as high priority by the business.

Low Severity & Low Priority(S4 & P4) :
1) If there is a spelling mistake on the pages which has very less hits throughout the month on any website. This fault can be considered as low severity and low priority.