The Alerts API allows a web page or app to deliver notifications that are shown outside of the page at the system level; this enables web apps to transmit information to users even while the program is idle or in the background. System notifications often relate to the operating system's primary notification mechanism: consider how a normal desktop system or mobile device distributes notifications. Of course, the system notification system will differ depending on the platform and browser, but this is OK since the Notifications API is designed to be broad enough to work with most system notification systems. To learn more about " notifications API"