What does a webhook represent in web development?

A webhook represents a method in web development that enables one application to send real-time data to another whenever a specific event occurs. This communication is typically achieved through HTTP requests, where the sending application makes an API call to a predefined URL when certain criteria are met, effectively functioning as a reverse API call.

By utilizing webhooks, developers can automate workflows and integrate systems without requiring the receiving application to continuously poll for changes. Instead, the data is sent only when necessary, making resources more efficient and reducing unnecessary network traffic. This event-driven architecture is particularly advantageous in scenarios where timely data transfer is critical, such as payment notifications, status updates, or user activity logs.

The other options do not accurately capture the essence of a webhook. User-initiated API requests imply that the user actively triggers the action rather than the event autonomously triggering it. Formal API specifications refer to the documentation that defines how an API operates, which does not involve automated, event-driven communication. Documented API endpoints describe the locations where APIs can be accessed, but they do not specifically pertain to the real-time, event-driven interactions characteristic of webhooks.