The proposed work will describe the field from its early work, through current approaches, before presenting our view for the future of this area. The authors will introduce the concept of soft biometrics; offer a historical perspective of the importance of these attributes; present a taxonomy to characterize various soft biometric traits; describe in detail the algorithms that have been used to automatically extract soft biometrics from face, fingerprints, iris, gait and voice; describe methods to fuse soft biometric information with primary biometric cues such as face and fingerprints; review the privacy and security implications of utilizing soft biometric traits in applications; and enumerate the research challenges in successfully incorporating soft biometric solutions in large-scale biometric systems. This book will include a number of tables and figures to convey the material being discussed and an extensive bibliography reflecting the large number of scholarly articles published on this topic.