Step-up authentication is a security approach that enhances user identity verification by requiring additional authentication for high-risk actions, thereby balancing security needs with user experience. Unlike traditional methods that authenticate users once at login, step-up authentication targets specific actions or resources, such as accessing sensitive data or performing high-value transactions, providing an extra layer of security without burdening users with unnecessary friction. This method allows organizations to focus security resources on critical touchpoints, improve regulatory compliance, and reduce fraud risk, all while maintaining a user-friendly experience. Step-up authentication differs from adaptive authentication by using predefined triggers based on user actions rather than contextual risk signals, and contrasts with authentication gateways and access controls by applying additional security during an existing session. Its successful implementation involves assessing risk, selecting appropriate authentication methods, designing user-friendly experiences, and continuously monitoring and refining the process to ensure both security and user satisfaction.