Notification backend and UI for the notification panel/icon. Used for notifications of other apps (announcementcenter, federatedfilesharing etc.)
Note: In ownCloud 8.2 the app hides itself, when there is no app registered, that creates notifications. In this case the bell and the dropdown are not accessible.
For information how to make your app interact with the notifications app, see Sending and processing/"mark as read" notifications as an ownCloud App in the wiki.
If you want to present notifications as a client, see Reading and deleting notifications as an ownCloud Client.