How Double tap to wake screen works?

DOuble tap to wake is now available on almost all phones out there, except Samsung phones. In apple iPhone 10, instead of double tap its single tap, but the working mechanism is same. When ever you turn on the double to wake option in settings, it simply keeps the touch digitizer active all the time until you turn it back off or power off your phone completely. When you lock your phone, the screen goes off, but keeps the digitizer on so that it can detect fingerprints and wake up the screen.

Simpl, but eats battery more. Not That Much

In Samsung phones, you can flash custom ROMs which have double tap to wake option available, and simple enjoy the feature.