Library Management System ER diagram models a complete book lending workflow with seven core entities: MEMBER, LIBRARIAN, BOOK, CATEGORY, TRANSACTION, FINE, REPORT, and RESERVATION. Members check out books through TRANSACTION records managed by librarians, with automatic FINE generation for overdue returns and RESERVATION support for unavailable titles. The schema enforces referential integrity via foreign keys linking transactions to members, books, and librarians, while category classification and fine tracking enable operational reporting. Fork this diagram to customize for academic libraries, public systems, or integrated library software (ILS) implementations. The mandatory/optional relationship indicators (solid/dashed lines) guide database constraint design and application logic for checkout workflows.