Definition
Syslogs contain subsets of information on faults, events, audit & session data, all related the monitored objects. Not all logs depict errors. Syslog can include audit and event logs.
Syslog Facilities
Any program or process capable of generating syslogs.
Syslog Severities
aka syslog severity levels or syslog priorities. The describe different levels of importance. Example of syslog severities: emergency, alert, critical, informational, warnings.
How Linux implements logging
rsyslogd
Verify the version of rsyslogd deployed on a RHEL machine: