Webhook

A webhook is a method where a system, the moment an event happens, sends an automatic message to a predefined address; instead of another system repeatedly asking “anything new?”, it announces the news itself.

A webhook is the “call me, I won't call you” pattern, and its value is in being live: instead of periodic polling that is both late and wasteful, the event is announced to the destination the moment it happens. Its common use is automation: when a threshold is crossed or an important event occurs, a webhook can send an alert or trigger a reaction in another system. But two things must be known. First, a webhook is a data-egress path, so the destination's security and authentication matter so data does not go to the wrong place. Second, a webhook is for events and notifications, not bulk data export; if you want to take all the data out, a webhook is the wrong tool and you should reach for an export or an API. A webhook is narrow and momentary, not a high-volume pipe.