A biometric identifier is a physical or behavioral trait used to recognize a person, such as a fingerprint, facial geometry, iris pattern, gait, or voiceprint. Unlike a password, it is tied to the human body or behavior and usually cannot be changed if exposed. In cyber security, that makes biometric data highly sensitive: it can be used for authentication, fraud, surveillance, or identity linkage across systems.
Biometric identifiers appear in real attacks when criminals steal voice samples, photos, or other traits to support impersonation and account takeover. For example, recorded speech can be analyzed to create a voiceprint or used to train voice-cloning tools for social engineering. Defenders reduce risk with strict collection notices, explicit consent, limited retention, encryption, access controls, and deletion workflows. Security teams also need to track derived data, because feature vectors and model embeddings may still qualify as biometric data even when the original recording is gone.