Books are classified on the shelves according to the Dewey Decimal System and according to Author's last name if the book is fictional. Some libraries will maintain sections of popular types of books such as mysteries or romance or bestsellers or new books. There are reference books with their classification (also part of the Dewey Decimal System). If you look inside the first few pages of a book you will see the Library of Congress ISB number that is assigned to published books. Then you will the Dewey Decimal System number, the genre of the book and the name of the Author and when it was published. This is true for both non-fiction and fiction books and reference books.
- 000 - Computer science, information & general works
- 100 - Philosophy and psychology
- 200 - Religion
- 300 - Social sciences
- 400 - Language
- 500 - Science (including mathematics)
- 600 - Technology
- 700 - Arts and recreation
- 800 - Literature
- 900 - History, geography, and biography