In simple words, webhook is a feature that allows one application to send automated information to another application. It’s an HTTP callback with which you can connect a platform with your preferred applications, so that you can keep a track of all the actions happening in your account.
When a certain thing happens, a webhook immediately sends an event notification. This is generally an HTTP request sent through your application.
Webhooks help you to create a powerful and integrated workflow across different apps. Here, the pre-requested information is passed to your preferred application, unlike the regular APIs where you have to manually poll data at regular intervals.
This ensures that, you receive instant and real-time notification for each specified event. For example, you can see every incoming call or message without having to leave your CRM application.
You can easily integrate the 3rd party applications like Zapier, ZenDesk, SalesForce, Mailchimp etc. through webhook integration. Please refer to this article to know the process in detail.