If you borrow a book and someone else requests it, the library may recall it. This means the due date will change, so that the book can be made available to the requester. You will receive an email asking you to return the book and advising you of the new due date. The book becomes overdue if it is not returned by the new due date and fines will be charged to your account.
This system is in place to ensure that books are circulated fairly among library users.