Biometrics
Authentication using unique physical or behavioral traits such as a fingerprint, face, or voice.
Biometric authentication↗ uses unique biological and behavioral traits, a fingerprint, face, iris, voice, or hand geometry, to verify identity. It relies on the "something you are" factor: instead of a password you must remember or a device you must carry, your own physical characteristics act as the key.
The main advantages are convenience and resistance to impersonation: biometrics↗ can't be forgotten, aren't easily handed to someone else, and are hard to copy in well-designed systems. That is why they are used everywhere from unlocking phones to airport checkpoints.
Biometrics are not absolutely secure, however. Fingerprints or faces can sometimes be spoofed, and more importantly, while a leaked password can be changed, your biometric data is permanent, it can't be "reset" if stolen. For that reason biometrics are usually used as one factor within multi-factor authentication, and it matters that biometric data is stored securely on-device rather than sent to a server.