---
title: Triggers
description: 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...
url: https://www.elastic.co/elastic/docs-builder/docs/3016/explore-analyze/alerting/watcher/trigger
products:
  - Elasticsearch
applies_to:
  - Elastic Stack: Generally available
---

# Triggers
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 [`schedule`](https://www.elastic.co/elastic/docs-builder/docs/3016/explore-analyze/alerting/watcher/trigger-schedule) triggers are currently available.