---
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://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4306/explore-analyze/alerts-cases/watcher/trigger
products:
  - Elasticsearch
---

# 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://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4306/explore-analyze/alerts-cases/watcher/trigger-schedule) triggers are currently available.