Two-factor authentication (2FA) or multi-factor authentication (MFA) is a security method that requires you to prove your identity in more than one way before accessing an account or system. Instead of just entering a password, you might also need to enter a code sent to your phone, use a fingerprint scanner, or confirm through an app. Government websites handling sensitive information—like tax filings on the CRA website or accessing your Service Canada account—often use MFA to protect citizens' personal data from hackers and identity theft.