Before you can authenticate or identify yourself using a biometric system, you must enroll yourself to this system. To enroll to the system it requests fingerprints, a voice recording or another biometric factor which is registered in the database as a template linked internally to a user ID. The next time when you want to authenticate or identify yourself, the biometric input is compared to the template(s) in the database by a matching algorithm which responds with acceptance (match) or rejection (no match).
