UPDATED TO CLARIFY HOW TO MANAGE PUSH NOTIFICATIONS
Firefox for Windows, Mac and Linux now lets you choose to receive push notifications from websites if you give them permission. This is similar to web notifications, except now you can receive notifications for web sites even when they’re not loaded in a tab. This is super-useful for websites like email, weather, social networks and shopping, which you might frequently check for updates.
You can manage your notifications in the Control Center by clicking the green lock icon on the left side of the address bar. You can learn more about how to manage push notifications here
Push Notifications for Web Developers
To make this functionality possible, Mozilla helped establish the Web Push W3C standard that’s gaining momentum across the Web. We also continue to explore the new design pattern known as Progressive Web Apps. If you’re a developer who wants to implement push notifications on your site, you can learn more in this Hacks blog post.