Android 4.4 Kit Kat introduced something called Immersive Mode. Basically, this means users are able to go full screen. Immersive Mode is a good option for games and reading apps and allows the system status and navigation bars to be hidden, thus adding a bit more real-estate to the screen. Immersive Mode also removes some of the distraction. The catch comes in with app support though, this is something developers have to enable.