What is Webhook?
A webhook is a way for one system to notify another the moment something happens, by sending an automatic HTTP request to a pre-agreed URL. Instead of your software repeatedly polling "has anything changed?", the other service pushes the event to you — "payment succeeded", "message delivered", "form submitted" — as it occurs, usually as a small JSON payload your server processes instantly.
Webhooks are the glue of modern business automation. An Indian event platform receives a Razorpay webhook when a buyer pays and immediately issues the QR pass; a WhatsApp system receives a webhook per incoming customer message and triggers the chatbot. Because the receiving URL is public, webhooks are verified with signatures — the sender signs each payload so forged notifications from attackers are rejected.