Biometrics is a rapidly evolving field with applications ranging from accessing ones computer to gaining entry into a country. The deployment of large-scale biometric systems in both commercial and government applications has served to increase the publics awareness of this technology. This rapid growth has highlighted the challenges associated with designing and deploying biometric systems. Indeed, the problem of biometric authentication is a Grand Challenge in its own right. Significant growth in biometric research in recent years has resulted in the development of innovative sensors, new algorithms, enhanced test methodologies and novel applications. The Handbook of Biometrics comprises chapters authored by prominent Biometric researchers describing the fundamentals and the latest innovations in their areas of expertise. This unique and timely volume is designed for researchers and advanced-level students in computer science. It is also suitable for Biometric and Computer Security professionals.