Originally Posted by gotvitamink
hardware. I think its a type of accelerometer.
As far as I know it IS an accelerometer. Same thing I would say. Don't have much knowledge, but it's basically the same technology the iPhone uses. It can detect how you're holding your phone. Yes, you could use your front camera on your phone as a accelerometer and it's been asked before, but no one attempted to do so since it would consume too much battery.
Nexus 5: Paranoid Android
Samsung Blackjack > AT&T Tilt > HTC Fuze > HTC Touch HD > HTC HD2 > Motorola Atrix > Samsung Galaxy Note > HTC One