18 U.S.C. Sec. 1028(D)(1) defines an "Authentication Feature" as a digital image, a biometric identifier, or other characteristic that: (1) is unique to an individual; (2) is capable of verification; and (3) is used for authentication purposes. There are four main types of Authentication Feature: digital images, biometric identifiers, other characteristics, and authentication technology. Digital images are typically used to verify a person's identity, such as a photograph or a signature. Biometric identifiers are unique physiological or behavioral characteristics of an individual, such as a fingerprint or facial recognition. Other characteristics can include personal information such as a Social Security number or a driver's license number. Authentication technology is a system used to authenticate a person's identity, such as a password or PIN.