Syslog
An industry standard message logging protocol. In networking, Syslog is used to log a wide assortment of ‘events’ on a device, such as interface status, changes in neighbor statuses in a dynamic routing protocol, system restarts, and many more. The information these logs store, including their timestamps, is often invaluable for troubleshooting network issues.
Syslog messages can be stored locally on a device, or sent to an external Syslog server.
Outside of networking, Syslog is also used for logging on host/client devices (Windows, MacOS, Linux, etc.) to track system changes, user activity, and other information.