[[trigger]]
=== Trigger

Every watch must have a `trigger` that defines when the watch execution process should start. 
When you create a watch, its trigger is registered with the appropriate _trigger engine_. 
The trigger engine is responsible for evaluating the trigger and triggering the watch
when needed.

Watcher is designed to support different types of triggers, but 
only  time-based <<trigger-schedule, `schedule`>> triggers are currently available. 

include::trigger/schedule.asciidoc[]