Just as fingerprints are unique to each individual, so are eyes, voices, hands, and facial features. Technology based on biometrics, the mathematical and statistical analysis of biological data, measures these features to differentiate one person from another. Although improved biometrics technology has been associated with reduced costs and many claim that the technology is a cost-effective identification tool, questions have been raised about whether biometrics technology constitutes an invasion of privacy. Numerous examples are provided of how biometrics technology has been used in the United States and abroad to identify individuals based on their physical characteristics.