To best coordinate and calibrate a response to your issue, it is helpful to understand the impact of a problem on your business.
Severity 1 - Business Critical Failure
Issues resulting in a total disruption of work, usually with one or more of the following characteristics:
Production systems are down
Products are unusable
No workaround is available
Severity 2 - Business Impacting Failure
Issues resulting in a partial disruption of work, usually with one or more of the following characteristics:
Production systems major functionality failure
Product use is severely restricted, although some work can continue
Workarounds are available
Severity 3 - Minor Functionality Failure
Issues representing an inconvenience to or minor disruption of work, usually with one or more of the following characteristics:
Production systems are up, but not operating as expected
Product use is affected or slowed
Workarounds are available
Severity 4 - Request for Information or Acknowledgement
Issues representing no loss of work, often one of the following:
Requests for documentation or other general information
Enhancement requests