Since the 1990s, biometric technologies have become an important element of border control throughout the world. Through digital analyses of body parts and bodily substances, biometric technologies are used to identify and categorize individuals in order to monitor and control their mobility. Biometric technologies are generally presented and promoted as scientifically based, exact and neutral methods of identification and verification. Biometric registration, identification and control can thus be carried out in the multiplicity of sites where migrants are bodily present, thereby promising to provide a more comprehensive way to ‘protect the secure and developed world from the incursions of the poor and insecure’. Classic fieldwork-based anthropology, with its focus on describing and analysing different cultures and societies, was not particularly concerned with the significance of the borders that separated such entities. The chapter also presents an overview of the key concepts discussed in this book.