This original PKI Note published by the erstwhile PKI Forum states, "Authentication can be performed with three approaches: knowledge factor (something the individual knows), possession factor (something the individual has), or biometric factor (something physiologically unique about the individual). Biometric technology uses a measurable biological or behavioral characteristic to reliably distinguish one person from another. Biometrics can enhance PKI technology, and, symbiotically, PKI technology can secure biometric technology. These PKI Notes discuss the basics of biometric technology and its synergistic combination with PKI technology".