What is the fingerprint sensor?
The fingerprint sensor module is small, and nicely built and it uses some advanced DSP (Digital Signal Processing) chips inside.
The sensor works like this. It is an optical sensor, which means it analyzes the photo of a finger. It then renders the image, makes some calculations, finds the features of that finger and then searches in its memory for a fingerprint with the same characteristics. It can achieve all that in less than a second!
The Fingerprint Sensor Module
Connection with Arduino Uno