MVC (Model-View-Controller) architecture is a widely used design pattern in Web Technologies for developing scalable, maintainable, and organized web applications. It separates the application into three major components: Model, View, and Controller. The Model represents the data and business logic, the View manages the user interface, and the Controller handles user requests and connects the Model with the View. The MVC architecture of a web application can be represented as: ``` User | v +-----------+ | Controller| +-----------+ | ----------------- | | v v +----------+ +-----------+ | Service | | View | +----------+ +-----------+ | v +-----------+ | Repository| +-----------+ | v +-----------+ | Database | +-----------+ ``` In a Spring-based web application, the Controller receives HTTP requests from users, the Service layer contains application logic, the Repository layer communicates with the database, and the View displays the response to the user. The database design of a library management application contains different entities and relationships. The main entities are Book and User. A User can borrow multiple books, and a book can be associated with borrowing records. The relationship between users and books can be maintained using a transaction or issue table. Database entities: ``` User ---------------- user_id (PK) name email password role Book ---------------- book_id (PK) title author price category Issue ---------------- issue_id (PK) user_id (FK) book_id (FK) issue_date return_date ``` Entity relationship diagram: ``` +---------+ +---------+ +---------+ | User |1 M| Issue |M 1| Book | +---------+----------+---------+----------+---------+ |user_id | |issue_id