Priority vs Severity

Often when filing a bug against a product you are working on or beta testing the question of what to set the priority and severity to come into play.

Severity is simply a rating of the effect of the bug/issue. For instance a bug that causes the application to crash with data loss would be a high severity issue. By contrast a dialog that has a mispelled word would have a low severity.

By contrast priority tends to inform the location of where a bug is found or the frequency it is encountered. For instance if the data loss only occurs on one in a million customer scenarios and it takes a very specific and hard to reach combination of mouse clicks to reach that point the priority of the issue may be very low. However a mispelled word on the welcome splash screen would have a higher priority as this will be seen by everyone.

Using these standards it is quite possible to have a high sev low priority bug in a product. It is also possible to have a low sev but high priority bug.

The priority of the bug may be influenced by the severity of the issue as priority also tries to denote when the bug will get fixed. Because of this priority can become very subjective and is usually left up to the person or team responsible for triaging the issue. Severity is much more black and white as it simply states the effect.