How does "two-factor authentication" enhance security?

Two-factor authentication significantly enhances security by requiring two distinct forms of verification before granting access to an account or system. The first factor is typically something the user knows, such as a password. The second factor is usually something the user possesses, which could be a smartphone app that generates a time-sensitive code, a hardware token, or a biometric input like a fingerprint.

This dual layer of security vastly reduces the likelihood of unauthorized access, as it is much harder for an attacker to gain both the user's password and the second form of verification simultaneously. For instance, even if a password is compromised through phishing or other malicious means, the requirement for a second authentication factor provides an additional roadblock that helps to protect sensitive information and systems.

In contrast, the other options mentioned do not directly address the concept of two-factor authentication. Encryption is a vital security measure, but it does not involve user verification processes; it is focused on data protection. Limiting access based on time is more about access control than authentication. Monitoring user patterns, while useful for identifying anomalies that might indicate a security issue, does not serve the purpose of verifying a user's identity at the point of access. Thus, the primary mechanism of increasing security through two-factor authentication lies in its requirement for