Biometrics is a general term used alternatively to describe a characteristic or a process. As a characteristic: a biometric is a measurable biological (anatomical and physiological) and behavioral characteristic that can be used for automated recognition. As a process: a biometric is an automated method of recognizing an individual based on measurable biological (anatomical and physiological) and behavioral characteristics. The term biometrics comes from the Greek words bios, meaning life, and metron, meaning measure.
Biometrics can be defined as measurable physiological or behavioral characteristics, or both, that can be utilized to verify the identity of individuals and include fingerprint verification, hand geometry, facial recognition, iris scanning, retinal scanning, voice recognition and signature verification. Biometric authentication is considered the automatic identification, or identity verification of an individual using either a biological feature they possess (physiological characteristic like a fingerprint) or something they do (behavioral characteristic, such as a signature). For authentication purposes, an individual must first be enrolled in a biometric system and the system must verify the claimed identity by comparison with a reference template. In this paper Part 1 consist of the introduction of various types of biometrics systems. Part 2 gives brief comparison of the commonly used biometrics systems and their applications. Part 3 explains how biometric system works. The biometric system performance depends on the matching score is explained in part 4. The conclusion is given in part 5. At last references and bibliography are given.