Flag for View.SystemUiVisibility: View has requested that the system navigation be temporarily hidden.

This is an even less obtrusive state than that called for by View.SystemUiFlagLowProfile; on devices that draw essential navigation controls (Home, Back, and the like) on screen, SYSTEM_UI_FLAG_HIDE_NAVIGATION will cause those to disappear. This is useful (in conjunction with the WindowManagerLayoutParams.FLAG_FULLSCREEN and WindowManagerLayoutParams.FLAG_LAYOUT_IN_SCREEN window flags) for displaying content using every last pixel on the display.

There is a limitation: because navigation controls are so important, the least user interaction will cause them to reappear immediately. When this happens, both this flag and View.SystemUiFlagFullscreen will be cleared automatically, so that both elements reappear at the same time.

[Android Documentation]