Library Website System class diagram models core entities—User, Student, Librarian, Transaction, and Book—with inheritance and association relationships. Students and Librarians inherit from User, while Transactions link Students to Books with borrowDate and returnDate tracking. This UML design demonstrates object-oriented principles for managing library operations, including user authentication, book searches, borrowing workflows, and librarian updates. Fork and customize this diagram on Diagrams.so to extend functionality like fines, reservations, or multi-branch support.