These are notifications sent to Apple devices, appearing on the lock screen, in the Notification Center, or as banners. For example, a news application might use these to immediately inform users of breaking headlines, bypassing the need for the user to actively check the app for updates.
The significance of these notifications lies in their ability to re-engage users, deliver timely information, and enhance the overall user experience. Originally introduced with iOS 3.0, these alerts have evolved into a critical channel for application developers to maintain user awareness and prompt interaction. They are key to app engagement, and facilitate everything from immediate news updates to e-commerce promotions.