log

For producing final messages before application’s death.

For detailed system behavior reports and diagnostic messages to help to locate problems during development.

For severe failures that affects application's workflow, not fatal, however (without forcing app shutdown).

For general information on the application's work.

A special log level used to turn off logging.

For pervasive information on states of all elementary constructs.

For indicating small errors, strange situations, failures that are automatically handled in a safe manner.

logger storage.