This document discusses various types of biometrics that can be used for authentication, including hard biometrics like fingerprints, soft biometrics like build and mannerisms, and behavioral biometrics like gait and typing patterns. It notes that biometrics can be classified based on what is analyzed, such as frequency for speech or speed and pressure for signatures. The document also discusses common biometric sensors, methodologies for analyzing sensor data, and the benefits and disadvantages of different biometric factors and sensors. It promotes the idea that continuous authentication using multiple biometrics can provide more secure access than single-factor authentication.