D46 biometrics

Unique or nearly-unique characteristics of the individual (something you are) are used to authenticate identity. Examples include finger prints, voice prints, retinal blood vessel patterns, DNA sequences, and facial characteristics.
While the overall field of biometrics identification and authentication is quite complex, these methods are normally used to authenticate identity or differentiate between identities from relatively small populations (typically a few thousand individuals), and this process is feasible with fairly common data correlation techniques.

Unique or nearly-unique characteristics of the individual (something you are) are used to authenticate identity. Examples include finger prints, voice prints, retinal blood vessel patterns, DNA sequences, and facial characteristics.