A webhook is an automated event triggered when something happens.
More specifically, a webhook is a HTTP request triggered by an event in a source system, that will be sent to a destination system, often with a payload of data. For example, when a website goes down, an automated call might send the admin an email. Webhooks are commonly used to perform small requests and tasks that don't need an entire API. They are automated; meaning they are automatically sent out when their event is fired in the source system. This focuses a testers attention on validating all the ways that the event could be triggered and ensuring that the HTTP request is sent and received as expected.
More specifically, a webhook is a HTTP request triggered by an event in a source system, that will be sent to a destination system, often with a payload of data. For example, when a website goes down, an automated call might send the admin an email. Webhooks are commonly used to perform small requests and tasks that don't need an entire API. They are automated; meaning they are automatically sent out when their event is fired in the source system. This focuses a testers attention on validating all the ways that the event could be triggered and ensuring that the HTTP request is sent and received as expected.