Webhooks are ways of augmenting or changing the behavior of web pages with customized callbacks. These callbacks can be used by third-party users and developers who are not related to the original website. Webhooks are typically used to connect two different applications in real-time for sending event data and are seen as an extension of APIs. 

For example, webhooks can be used to inform marketers in real-time when product information is updated, payment is completed, or when a refund is requested.