Biometrics refers to the automatic identification of a person based on physiological or behavioral characteristics. There are two main types: physical biometrics like fingerprints and facial recognition, and behavioral biometrics like voice recognition and signature analysis. Biometric systems use sensors to capture data, processing to extract templates, storage to save templates, and interfaces to communicate decisions. They work by enrolling templates during registration and verifying identities during authentication by comparing live samples to stored templates.