Syslog messages are a common method of event logging, and it is a standard feature of Unix computing systems and most network devices like firewalls, switches and routers. Messages received by a Syslog Daemon are usually logged to disk. The messages can be split into different files depending on the priority of the message.

Syslog messages usually consist of a priority, a message header, and the message text.

For example:

<180>Jan 14 21:56 seibu [process] This is my message

The priority is 180
The message header contains: the current date, originating server, and process name.
The message text is the rest of the message.

The BSD syslog format is discussed further in the RFC3164 at:
http://www.ietf.org/rfc/rfc3164.txt