Webhook

A webhook is an HTTP call one service fires automatically to a URL supplied by another service, at the exact moment an event occurs: a missed call comes in, an appointment is booked, a form is filled. It's the opposite of polling, where a system asks the other at regular intervals ("anything new? anything new?"). The webhook pushes the information at the right time, with no waste — the difference between having mail delivered and checking the box every morning.

For a small business, the webhook is invisible but central: it's what lets a missed call trigger a text, create a CRM record, and hold a slot — without any human clicking anything. The hygiene rules are simple: the URL must be HTTPS, the message signature must be verified (to prove it really came from the claimed sender), and the receiving system must reply fast — a webhook isn't meant to do the work, just to announce there is some. Complex orchestration is then delegated to a tool like Zapier.