A webhook is an automated notification sent from one application to another when a specified event occurs.
An event pushes a notification
A webhook sends an HTTP request when something happens, such as a payment succeeding or a build finishing. The receiving system can react without repeatedly asking whether anything changed.
Reliable delivery takes work
Receivers should authenticate requests, respond quickly, and process event identifiers idempotently. Queues and retries help when the destination is temporarily unavailable.