A direct fingerprint reader (DFR), also called a fingerprint scanner or fingerprint reader, is a biometrics device that uses automated methods of recognizing a person based on unique physical characteristics of a person’s fingerprint.
A fingerprint is made up of a pattern of ridges and furrows as well as characteristics that occur at minutiae points (ridge bifurcation or a ridge ending). Fingerprint scanning essentially provides an identification of a person based on the acquisition and recognition (or verification) of those unique patterns and ridges in a fingerprint.
Image Source: MSU Biometrics (2004)
Fingerprint devices are by far the most popular form of biometric security used, with a variety of systems on the market intended for general and mass market usage.