Velocity Alerts!

This application receive notification from Velocity

A notification is a message you can display to the user outside of Velocity application's normal UI. When you tell the system to issue a notification, it first appears as an icon in the notification area. To see the details of the notification, the user opens the notification drawer. Both the notification area and the notification drawer are system-controlled areas that the user can view at any time.

This allows a smartphone to receive and display text or image message alerts even when the device's screen is locked and the social media application that is pushing the notification is closed. Different devices and services rely on different methods to deliver notifications.