Can you list the main levels of logging used in systems?

Main logging levels commonly used in Java and other systems include:

• TRACE — the most detailed level, used for in-depth tracking of program execution.
• DEBUG — for debugging, contains information useful to developers.
• INFO — informational messages about the normal operation of the application.
• WARN — warnings about potential issues that do not stop the operation.
• ERROR — error messages that affect operation but do not cause a crash.
• FATAL — critical errors that usually lead to application shutdown.

Example of usage with the SLF4J library:

logger.debug("Debugging info: variable value = {}", value);
logger.error("An error occurred while processing the request", exception);