I have a service running in the background and I want to notify user if there is a new data, I've used a notificationmanager, and the notification appears. Notifications provide short, timely information about events in your app while it isn't in use.Notifications also appear on paired wearables. Status bar and notification drawer. REAN is a FREE emergency notification tool for ALL citizens of Bexar County. This system uses the Bexar Metro 911 landline database for emergency notifications. You can change settings for certain apps or for your whole phone. Notifications show when you swipe down from the top of your screen. When a notification arrives, an icon usually appears in the status bar. This signals to the user that there's something to see in the notification drawer.