Webhook
Webhooks are also sometimes referred to as “Reverse APIs”. In APIs, the client-side application calls (consumes) the server-side application. Whereas, in case of web hooks it is the server-side that calls (consumes) the web hook (the end-point URL provided by the client-side application), i.e. it is the server-side application that calls the client-side application.
Webhooks operate on the concept of “event reaction” (don’t call me, I’ll call you if I have something new), and thus avoids the need for constant polling of the server-side application by the client-side application. Thus, rather than the client-side application constantly polling the server-side application to check for new events, the server-side application calls the client-side application (by invoking a client provided webhook URL) anytime the server-side has something new to report to the client.
This is the core concept of the Webhook.
----------------------------------------------------------------------------------------------------------------
What WebHooks are used for
