UNESCO defines a book as: any printed matter with more than 49 pages, excluding the front cover and back cover, published by a publishing house (enterprise), with a specific title and author's name and an international standard book number, is called a book.
Books are works recorded on certain forms of materials with words or other information symbols for the purpose of spreading knowledge. Books are the product of human social practice, and they are a specific and developing tool for knowledge dissemination.
In ancient China, people gave different definitions to books. For example, from the content of the book, there are: "six hundred schools, the general name of the book" ("preface to the history"). From the point of view of book style, it is considered that "it was written in a book named bamboo and silk" (Preface to Explaining Words). Obviously, these definitions are the products of the times, based on the actual situation at that time, and it is impossible to make a comprehensive summary of the future development. However, the above definition has correctly revealed the content and formal characteristics of books at that time, and "book" as a specific concept is different from the original written records. After thousands of years of evolution, the scope of knowledge as the content of books has expanded, the methods of description and expression have increased, and the material carriers and production methods used have also changed many times. As a result, various types of books, writing methods, carriers, book systems and various modes of production have emerged. All these have prompted people to have a more systematic and clear concept of books.
Until today, books are divided into broad and narrow sense. In real life, we are often late for some interesting phenomena: for the concepts of "library" and "library and information work", "book" is a broad sense, which refers to all kinds of reading materials, including Oracle Bone Inscriptions, epigraphy rubbings, hand-scrolls, contemporary publications, newspapers, and even audio-visual materials, simple emblem films (volumes), machine-readable catalogues and other new technology products; In the practical work of library and information institutions, people should compare books with periodicals, newspapers, scientific and technological reports, technical standards, audio-visual materials, microforms and so on. , but there are differences. When the former is different from the latter, the scope of the book is greatly reduced, which is the narrow sense of "book".