A webhook is an automated message that one system sends to a web address you specify as soon as a particular event occurs, such as a new order, a payment or a stock change. It lets software push information out instead of waiting to be asked.
With a standard API, your system must repeatedly ask another system whether anything has changed, which is called polling. A webhook reverses this. You register a receiving URL with the sending platform and choose which events you care about. When one happens, the sender makes an HTTP request to your URL containing details of the event, usually as JSON, and your system acts on it.
Retailers use webhooks to react quickly: an ecommerce order can create a pick task in the warehouse, a refund can update accounting, or a stock sale in store can adjust the online quantity within moments. Many payment and POS platforms offer them.
Webhooks need careful handling. The receiving endpoint must be available and respond quickly, or the sender may retry or give up. Messages can arrive twice or out of order, so the receiver should avoid processing the same event twice. Because anyone could send a fake request to a public URL, signatures or secret tokens should be verified before the data is trusted. Logging every incoming event makes problems easier to trace.
Webhooks matter because they make integrations faster and lighter than constant polling. Near real-time data keeps stock accurate, speeds up fulfilment and reduces the delays that frustrate customers.