1- Actors and Generalization: The User is the parent actor which generalizes the Student, Instructor, and Admin roles.all specific roles inherit the common behavior like performing a Login.
2- Core Associations: diagram shows where each specific actor interacts with their unique set of Use Cases (Student linked to Browse Courses, Admin linked to Manage Users).
4- (extend) links show optional behavior (enrolling in course is an optional extension when browsing courses).
==================================================
==================================================
==================================================
This class diagram illustrates an online learning management system where users (students, instructors, and admins) interact through services to manage courses, lessons, quizzes, and certificates. It also shows how data is stored and managed using a JSON-based database manager for persistence.
==================================================
