Webhook
also HTTP callback
A user-defined HTTP request that one app automatically sends to another's URL when an event happens, pushing data in real time instead of being polled.
Analogy
Like a doorbell: instead of you checking the door every minute, it rings you the moment someone arrives.
Why it matters
Webhooks are the fastest way to trigger automations the instant something happens, central to GoHighLevel custom webhooks and inbound triggers in n8n/Make/Zapier.
In practice
GoHighLevel sends a POST to your n8n webhook URL the moment a contact submits a form.