• DEBUG –Any information related to things that are going on in the program. These are often messages written by programmers for debugging purposes.
  • INFO –Any user-initiated action or any system operations such as scheduled tasks executing, or system startup and shutdown.
  • WARN –Any condition that could become an error state in the future. Library deprecation warnings, low available resources, or slow performance are examples of entries that would go in this level.
  • ERROR –Any and every error condition should go in this level.
  • FATAL –Any error condition that causes the system to shut down. For example, if the system needs 32 GB of memory on startup and 16 GB is all that’s available, the program should log a FATAL error message and immediately exit.