Two-factor authentication is the use of several separate layers of security to protect a device or network. Users attempting to access a device using two-factor authentication must pass two different types of “tests” before they can view any actual files or otherwise gain access. Perhaps the most common use of two-factor authentication is the use of the “ownership factor” in conjunction with the “knowledge factor”. In this case, the user will need to * enter a pre-generated number that changes at a set time and appears on a physical “token” that the user carries with them (ownership factor) and * enter into a password of the user’s choice (knowledge factor). Two-factor authentication can also include biometrics, such as fingerprint and retinal scans, which can be used in conjunction with another type of factor to form the basis for two-factor authentication.