What is the Smart Stay Feature on my Samsung Galaxy S III?
The Smart stay feature uses the front camera to sense when you are looking at your device, and it keeps the screen from turning off regardless of the screen timeout setting.
Turn On Smart Stay
To turn on the Smart stay feature, from the Home screen, touch Menu > Settings > My device > Smart screen. Place a check mark next to Smart stay to turn the feature on.
Smart stay may not work in the following situations:
When your device is docked or is not held upright.
When the front camera fails to detect your face and eyes.
When the source of the light is behind you or you are using your device in the dark.
When the front camera is being used in another application.