Biometric devices can be use for either IDENTIFICATION or AUTHENTICATION
ONE TO ONE is for AUTHENTICATION
This means that you as a user would provide some biometric credential such as your fingerprint. Then they will compare the template that you have provided with the one stored in the Database. If the two are exactly the same that prove that you are who you pretend to be.
ONE TO MANY is for IDENTIFICATION
A good example of this would be within airport. Many airports today have facial recognition cameras, as you walk through the airport it will take a picture of your face and then compare the template (your face) with a database full of templates and see if there is a match between your template and the ones stored in the Database. This is for IDENTIFICATION of a person.
Some additional clarification or comments that might be helpful are: Biometrics establish authentication using specific information and comparing results to expected data. It does not perform well for identification purposes such as scanning for a person's face in a moving crowd for example.
Identification methods could include: username, user ID, account number, PIN, certificate, token, smart card, biometric device or badge.
Auditing is a process of logging or tracking what was done after the identity and authentication process is completed.
Authorization is the rights the subject is given and is performed after the identity is established.
Reference OIG (2007) p148, 167
Authentication in biometrics is a "one-to-one" search to verify claim to an identity made by a person.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 38.
