Biometrics are the physiological and behavioural characteristics of individuals. This could be fingerprints, voice, face, retina and iris patterns, hand geometry, gait or DNA profiles. However, the legal definition of ‘biometrics’ may differ – in some contexts, it may be defined by law, whereas in others it may not have, or only have a vague, legal definition.
Biometrics used in ID systems are most commonly facial photographs, fingerprints, and iris scans.
If data like photographs are collected in the enrolment or data collection of an ID scheme, even if it is not immediately used for purposes like facial recognition, the existence of the dataset means that it can be used for such in the future, as in the case of India adding facial recognition to its biometric systems.