Dr. Davide Maltoni and Dr. Dario Maio are full Professors in the Department of Computer Science and Engineering at the University of Bologna, Italy. Dr. Anil K. Jain is a University Distinguished Professor at the Department of Computer Science and Engineering at Michigan State University, USA. Dr. Jianjiang Feng is an Associate Professor in the Department of Automation at Tsinghua University, China. The authors' extensive list of publications on biometrics include the Springer titles Encyclopedia of Biometrics, Introduction to Biometrics, Handbook of Face Recognition, Handbook of Biometrics, Handbook of Multibiometrics, Human Identification Based on Gait, Biometric Systems, Palmprint Authentication.