What is "two-factor authentication" in electronic access control?

Two-factor authentication is a security measure that requires users to provide two different forms of verification before gaining access to a system or account. This approach significantly enhances security by combining two independent elements that an authorized user must possess. These elements typically fall into three categories: something you know (like a password), something you have (like a smartphone or a security token), or something you are (like a fingerprint or facial recognition).

By requiring two forms of verification, two-factor authentication makes it much more challenging for unauthorized individuals to gain access, even if they have compromised one part of the authentication process. This method is widely used in electronic access control to protect sensitive information and secure areas, providing a robust defense against unauthorized access.

The other options do not accurately represent the principle of two-factor authentication. For instance, requiring just one form of verification would not qualify as two-factor authentication, while a procedure that blends physical and digital locks, or a technique for remote system monitoring, does not relate specifically to the requirement for multiple verification methods.