Security: Potential security issues.
Crash/Hang/Data Loss: Bugs which cause a machine to crash, resulting in an irrecoverable hang,or loss of data.
Performance: Issues that reduce the performance or responsiveness of an application.
UI/Usability: A cosmetic issue, or an issue with the Usability of an application.
Serious bug: Functionality is greatly affected, and has no workaround.
Other bug: A bug that has a workaround.
Feature (new): Request for a new feature.
Enhancement: Request for an enhancement to an existing feature.