FreebookX Book Sharing ER diagram models a complete peer-to-peer book exchange system with User, Book, BookRequest, Transaction, Review, Notification, and Message entities. Users with donor or seeker roles manage book listings organized by Category, while BookRequests trigger Transactions that culminate in Reviews and Notifications. The schema enforces referential integrity through foreign keys and supports asynchronous messaging between donors and seekers throughout the transaction lifecycle. Fork this diagram to customize entity attributes, add audit trails, or extend it for features like wishlists or book ratings aggregation. The design balances normalization with query performance, making it ideal for platforms prioritizing user trust and transaction transparency.