FireHydrant helps your team quickly assign a severity level to an incident, giving you a quick one line answer to the question "How important is this incident". When you set up your account FireHydrant will automatically create 5 severities for you, SEV1-SEV5. You can see these severities on the severities tab on the navigation if you are an account owner
Here you can see the 5 severities created by FireHydrant, from here you can delete, edit, or create severities based off of how your specific team and organization prioritize your incidents.
This page also includes the Severity Matrix which you can read more about here.