The term two-factor authentication (2FA) refers to a security mechanism that requires users to provide two different forms of identification to access an account or system. Typically, 2FA involves a combination of something the user knows, such as a password, and something the user has, like a mobile device that receives a verification code. This additional layer of security makes it significantly more challenging for unauthorized users to gain access, even if they acquire the password. 2FA is commonly used in online banking, email services, and other sensitive applications to enhance account security.