When used for identification purposes after enrolling, the biometric system seeks the entire database for matching patterns including, for instance, arches, loops and whorls (ridges) as well as bifurcations, crossovers and endings (minutiae).
If the input pattern matches a biometric template then the individual is identified. However, in theory, chances for false accepts, called the false accept rate, exist. That is why a second security measure, e.g. a badge or ID card, should be required to allow for additional verification or authentication.
If the input pattern does not match a biometric template, the individual’s biometric fingerprint is rejected, which could mean either that the individual’s template has not been enrolled, or there is an instance of a false rejection. Scanning more fingers will tell; fingerprinting has the advantage over other biometric systems that up to ten templates can be enrolled and used for recognition.
Please note that fingerprints cannot not only be used for identification but also for authentication as explained in our article Different Uses of Biometrics.