Two-step authentication uses two types of authentication to verify your identity. First, you need to log in with your SUNet ID and password. Then you need a physical device that you control—such as your mobile phone, tablet, or landline phone—to verify your identity. This type of authentication is required to access Stanford systems that have higher than normal levels of security, such as critical business or infrastructure systems. In addition, two-step authentication can help protect your Stanford account should someone else learn your password.