Notification channels enable us app developers to group our notifications into groups—channels—with the user having the ability to modify notification settings for the entire channel at once.In Android O this feature is introduced.Right now it is available developers preview.
|IMPORTANCE_HIGH||shows everywhere, makes noise and peeks|
|IMPORTANCE_DEFAULT||shows everywhere, makes noise, but does not visually intrude|
|IMPORTANCE_LOW||shows everywhere, but is not intrusive|
|IMPORTANCE_MIN||only shows in the shade, below the fold|
|IMPORTANCE_NONE||a notification with no importance; does not show in the shade|