What is a Push Notification?
A push notification is a type of notification that forces the display of a new message to the user's current interface. Depending on the application, these messages may either originate from a local application backend or remotely in the cloud.
It is a usable feature in both mobile and desktop applications and it entails any programming technique that pushes a notification to the frontend UI (usually on the OS layer) regardless of what app/s are currently open. Notifications can take the form of a popup dialog, banner, or other UI element that draws the user's attention.
Push Notification Use Cases
Push Notifications are commonly used in scenarios where timely notifications are desired. For example, in a mobile chat app, users will want to be notified when they receive a new instant message so that they can respond quickly. Push Notifications are not limited to instant messaging and can be adopted for use wherever it makes sense for the user to be notified "now" – whether it is a news website pushing latest articles to online readers, or simply an offline reminder for a calendar event.
Apple was the first company to introduce the idea, and implements Push Notifications for Safari and mobile apps with technology aptly named Apple Push Notification Service (APNS). Google uses Push Notifications in a similar way with Google Cloud Messaging (GCM) and Microsoft has its own API implementation that works on Windows 10 and Xbox.
You will likely have come across the permission prompt for allowing / denying Notifications at the top of your browser interface at some point. These Push Notifications are based on either Web Push or Push API.