1.3. Why is syslog-ng needed? The syslog-ng Premium Edition 7 Administrator Guide
Log messages contain information about the events happening on the hosts. Monitoring system events is essential for security and system health monitoring reasons.
The original syslog protocol separates messages based on the priority of the message and the facility sending the message. These two parameters alone are often inadequate to consistently classify messages, as many applications might use the same facility — and the facility itself is not even included in the log message. To make things worse, many log messages contain unimportant information. The syslog-ng application helps you to select only the really interesting messages, and forward them to a central server.
Company policies or other regulations often require log messages to be archived. Storing the important messages in a central location greatly simplifies this process.
For details on how can you use syslog-ng PE to comply with various regulations, see the Regulatory compliance and system logging whitepaper.