What does "event_handler_enabled" mean in hosts.cf

Nagios Nagios Configuration support
1

Can someone please explain to me what “event_handler_enabled” in hosts.cfg means? I know its used to determine whether the event handler is enabled or disabled but what does the event handler do or what is it used for?

Thanks in advance.

-Shawn

2

nagios.sourceforge.net/docs/2_0/
nagios.sourceforge.net/docs/2_0/toc.html
"Event handlers" link