Explanation:
Two-Factor Authentication (2FA) is a security measure that requires users to provide two forms of verification to access a system or service.

Typically, 2FA combines something the user knows (like a password) with something they have (like a smartphone or OTP) or something they are (like a fingerprint).

2FA provides an additional layer of security, making it difficult for attackers to access accounts even if passwords are compromised.

Additional Information:
Common 2FA methods include SMS-based OTPs, hardware tokens, and app-based authenticators like Google Authenticator. Biometric methods such as fingerprint and facial recognition are also gaining popularity.

Despite its effectiveness, SMS-based 2FA is vulnerable to SIM swapping attacks, prompting organizations to recommend app-based alternatives.

Formal Definition:
Two-Factor Authentication (2FA) is a security method that requires two distinct forms of verification to authenticate users and enhance access security.