This monograph describes the technology of biometrics both from technological and legal perspectives. The legal analysis focuses on EU law and the law of the Czech Republic. The first chapter titled “Biometric Technology” describes the nature and functioning of the technology. It provides various definitions to illustrate what can be considered biometrics. These definitions are then contrasted with the notion of biometrics in law. The chapter also identifies multiple risks related to biometrics. The second chapter titled “Biometrics from the Perspective of International and EU Law” describes the international and EU legal framework. The main focus is put on General Data Protection Regulation and individual national derogations in the area of regulating biometric data. The chapter also describes other laws related to biometrics and provides a perspective on future regulation of artificial intelligence that is utilized in biometric systems. The third chapter titled “Czech Legislation on Biometrics” assesses constitutional aspects of biometric regulation, current personal data protection legislation, as well as specific public laws that regulate the use of biometric technologies mainly for identification or verification of an individual’s identity. Moreover, this chapter describes the specificities of certain uses of biometrics. The fourth chapter titled “Data Subjects and Their Options with Regard to Protecting Own Biometric Data” describes the scope of individual freedom and autonomy of humans with regard to the use of biometric technologies. The chapter provides an overview of both legal and technical instruments that individuals may use for the protection of their biometric data. The fifth chapter titled “Recommendations for Data Controllers” provides guidelines to controllers on how to process biometric data lawfully and how to provide various safeguards to data subjects with regard to various levels of privacy protection. Finally, the monograph also contains Annex I. titled “Research Report on Augmented Indicative Values of Biometric Data.” This report provides an overview of what information can be derived from various types of biometric data, namely from fingerprint, face, iris, voice, and keystroke dynamics.