This is interesting. Remember those push notifications in Android and iOS. Mozilla is working to bring that to web browser. Mozilla is working to bring push notifications to Firefox on desktop, Android and on iOS. This is how it works:
- Every user will have a unique URL using which the website can push the notification to the user. This URL is given to the website when the website requests for permission and once the user accepts the request, notification service will generate a new URL that links the site to the user.
- The site sends a notification to the notification service using the URL
- Once the notification is arrived at the notification service, it is then delivered to all the user's devices where Firefox is installed.
Head to this wiki page for more information on this.