Two-factor authentication (2FA) is used to enhance security by requiring two forms of identification before granting access to an account or system. Typically, this involves something the user knows (like a password) and something the user possesses (such as a mobile device for receiving a code). The primary purpose of 2FA is to add an additional layer of protection beyond just a password, reducing the likelihood of unauthorized access even if a password is compromised. This is crucial in safeguarding sensitive information across various online services.