The live-chat-request trigger is a system default trigger. Every time a user requests a live chat you can assign a conversation flow to it.
In the following example, a Notification will be sent to all operators when there is a live chat request. (Notification block)
Another example of a system default trigger is the not-answered-chat trigger;
This trigger is automatically activated 2 minutes after the live chat request + in case none of the operators pick up the live chat request.