What is the term for an authentication method that requires two different factors to verify a user's identity?

The term for an authentication method that requires two different factors to verify a user's identity is Two-Factor Authentication. This method enhances security by combining two distinct forms of verification, typically something you know (like a password) and something you have (like a mobile device or a token).

By requiring these two different factors, Two-Factor Authentication reduces the likelihood of unauthorized access because even if one factor (such as the password) is compromised, the second factor still provides a layer of security. This dual requirement makes it harder for attackers to gain access to accounts and sensitive information.

While Multi-Factor Authentication is a broader term that encompasses any use of two or more verification factors (which could include more than just two factors), Two-Factor Authentication specifically refers to the use of exactly two factors. Single Factor Authentication employs just one method of verification, and Single Sign-On allows users to access multiple applications with one set of credentials, which does not inherently involve multiple factors for authentication.