The Web Push protocol allows your application to easily engage users by sending notifications to the browser. The subscription to these notifications are done by the user (opt-in).
The notification types depend on the application. For example, it could be a notification for an internal message or an alert before account closure.
We will see in this documentation that the Web Push API offers several options to customize the notifications by adding buttons, vibration schema, images, urgency indictor and more.
You want to test it? Please go to this demo page to see what your browser already supports.