The technology commonly used for authenticating online transactions is two-factor authentication (2FA). This security measure requires users to provide two distinct forms of identification before gaining access to an account or completing a transaction. Typically, this involves something the user knows, like a password, and something the user possesses, such as a mobile device receiving a one-time code. By combining these elements, 2FA significantly enhances security, making it harder for unauthorized users to gain access even if they have the password. It is widely adopted in e-commerce, banking, and sensitive online services.