Logs that describe an unrecoverable application or system crash, or a catastrophic failure that requires immediate attention.

Logs that highlight when the current flow of execution is stopped due to a failure. These should indicate a failure in the current activity, not an application-wide failure.

Logs that track the general flow of the application. These logs should have long-term value.

No level filtering is done on this log level. Log messages of all levels will be logged.

Logs that are used for interactive investigation during development. These logs should primarily contain information useful for debugging and have no long-term value.

Logs that highlight an abnormal or unexpected event in the application flow, but do not otherwise cause the application execution to stop.