How to Print Screen in android phones

Where’s the Print Screen button when you need to take a screen shot of your Android device? Instead of using one button, try a combination of two:

Press and hold down the Power and Volume-down buttons simultaneously.
Open the Gallery app, and you can see your screenshot already saved in the Screenshots album.

Note: Older Android system doesn't support this feature, but it has a more complicated way to take screenshots using Android SDK such as this without rooting the device.