Which identifier is used to describe the application or process that submits a log message?

The identifier that describes the application or process submitting a log message is known as the facility. In the context of logging systems, the facility refers to the source of the log message, which can be an application, a service, or a process. Each facility is assigned a unique identifier that allows system administrators and security professionals to categorize log messages according to where they originated. This categorization is crucial for effective monitoring, troubleshooting, and correlating logs from different sources.

For example, in syslog, different facilities represent different types of services (like mail, daemon, or user-level messages), which helps in filtering and managing log information efficiently. Using this identifier, one can quickly determine which application or process is generating logs, thereby streamlining incident response and analysis.

The other options do not serve this specific function; action relates more to what is being done with the log message, selector is less commonly used in this context, and priority indicates the severity level of the log message rather than its origin. Thus, the facility is the correct term for identifying the application or process submitting a log message.