The idea is based on the idea that one or more selected activities of an app can be started, displayed and used on the Android device without having to unlock the device. So an app that can be started and used from the lock screen. All other apps and settings remain hidden behind the lock screen, which is protected e.g. by a pin number, fingerprint or a pattern.

Details on the implementation can be found at http://www.dieletztedomain.de/android-kiosk-mode-app-so- gehts/.