Android 4.o (Ice Cream Sandwich) lets you unlock your phone by looking at it. Its ‘Face Unlock’ feature uses advanced facial recognition technology to analyze the structure of your face. The security option requires you to register your face during setup and then it only unlocks when it recognizes you.
If you select Face Unlock from the security menu, you will be walked through the steps to set it up. You will also need to choose a back up method of unlocking your phone in case it doesn’t recognize you.
The new version of Face Unlock in Android 4.1 (Jelly Bean) will require the user to blink before the phone unlocks. This added feature, called the “Liveness Check” ensures that static pictures can’t be used by someone else to unlock your phone.