The term "library books" refers to any written materials or resources that are available for borrowing from a library. These can include hardcover and paperback books, magazines, newspapers, audiobooks, e-books, and other printed materials that are owned by the library and made accessible to its patrons on loan. Library books are typically provided free of charge to anyone with a valid library card or membership, and they usually have to be returned at the end of their borrowing period so others can access them as well.