The use case diagram for a quiz application illustrates how users and administrators interact with the system. Users can register accounts, log in, take quizzes, review answers, and view their quiz history. They can also earn badges and analyze their performance based on quiz results. Administrators manage quizzes, create new quizzes, and generate performance reports. This diagram clearly demonstrates the functional relationships between different system components, emphasizing how the platform supports user engagement, assessment tracking, and learning management. It provides a clear visualization of user roles, activities, and dependencies essential for quiz application development and system documentation.