Priority and Severity

What is Severity ?

The degree of impact casted by the bug on an application .
Or 
Severity is the seriousness of the problem .
Severity:

• It is totally related to the quality standard or devotion to standard. 
• Severity means how severe it is affecting the functionality. 
• Severity is associated with standards. 
• The severity type is defined by the tester based on the written test cases and functionality. 
• Is related to technical aspect of the product. 
• It reflects on how bad the bug is for the system. 
• It is totally related to the quality standard or devotion to standard. 
• Severity means how big functionality is affecting of the product. 
• The Test Engineer can decide the severity level of the bug. 
• Based on Bug Severity the product fixes are done. 

What is Priority ?

Relative degree of precedence given to a bug for its fixation .
Or 

• Priority is the urgency of fixing a problem .
• Priority means how fast it has to be fixed. 
• Priority is related to scheduling to resolve the problem. 
• Severity means how severe it is affecting the functionality. 
• Is largely related to Business or Marketing aspect. 
• It is a pointer towards the importance of the bug. 
• The priority status is set based on the customer requirements. 
• Is related to technical aspect of the product. 
• It reflects on how bad the bug is for the system. 
• Priority means how urgently the issue can be fixed. 
• Product manager is to decide the Priority to fix a bug. 
• Based on ‘Project Priorities the product fixes are done. 
• The Priority status is set by the tester to the developer mentioning the time frame to fix a defect. If High priority is mentioned then the developer has to fix it at the earliest. 

Examples :

High Priority & High Severity:

1. All show stopper bugs would be added under this category (I mean to say tester should log Severity as High, to set up Priority as High is Project manager’s call), means bug due to which tester is not able to continue with the Software Testing, Blocker Bugs.
2. Let’s take an example of High Priority & High Severity, Upon login to system “Run time error” displayed on the page, so due to which tester is not able to proceed the testing further.

High Priority & Low Severity:

1.  On the home page of the company’s web site spelling mistake in the name of the company is surely a High Priority issue. In terms of functionality it is not breaking anything so we can mark as Low Severity, but making bad impact on the reputation of company site. So it highest priority to fix this.

Low Priority & High Severity:

1. The download Quarterly statement is not generating correctly from the website & user is already entered in quarter in last month. So we can say such bugs as High Severity, this is bugs occurring while generating quarterly report. We have time to fix the bug as report is generated at the end of the quarter so priority to fix the bug is Low.
2. System is crashing in the one of the corner scenario, it is impacting major functionality of system so the Severity of the defect is high but as it is corner scenario so many of the user not seeing this page we can mark it as Low Priority by project manager since many other important bugs are likely to fix before doing high priority bugs because high priority bugs are can be visible to client or end user first.

Low Priority & Low Severity:

1. Spelling mistake in the confirmation error message like “You have registered success” instead of successfully, success is written.
2. Developer is missed remove cryptic debug information shortcut key which is used developer while developing he application, if you pressing the key combination LEFT_ALT+LEFT_CTRL+RIGHT_CTRL+RIGHT_ALT+F5+F10 for 1 mins .