Biometric characteristics can be divided in two main classes: * Physiological are related to the shape of the body. Examples include, but are not limited to fingerprint, face recognition, DNA, palm print, hand geometry, iris recognition (which has largely replaced retina recognition), and odor/scent. * Behavioral are related to the behavior of a person. Examples include, but are not limited to typing rhythm, gait, and voice. Some researchers have coined the term "behaviometrics" for this class of biometrics.