In a Library, What Are the Three Types of Cards in the Card Catalog?

Subject

Subject listings in the card catalog are most helpful for a reader who isn't in search of a specific book, but would rather see all the books under a certain topic. All card catalogs list subjects and subdivisions of subjects based on criteria created by The Library of Congress. Subject cards will begin with the broadest topic (i.e., Literature) and then become more specific and subdivided (i.e., Literature-American; Literature, American, 1900-1945). Subject cards have "See Also" suggestions for similar topics other places in the card catalog.

Author cards in the catalog are fairly straightforward, listing the author alphabetically by last name. Authors of similar name can be differentiated by a middle initial or by their birth and death dates. If a book has multiple authors, the card catalog will give each of them their own author card with their co-authors listed, so that if readers know just one author they can still find the book. Authors using pen names will often have a "See Also" card under that name directing readers to the full listing elsewhere.

The title cards are filed alphabetically by the title of a book, not counting the article (The, A, An, etc.). In the card catalog, title cards are listed after author and subject cards when all start with the same word. Title cards will also contain the subtitle of the book. Like author and subject cards, title cards will contain the publishing date and number of pages.

Each author, title and subject card in the card catalog lists the location of the book in the library. Fiction books are generally shelved alphabetically by the author's last name, while non-fiction books are organized for the most part by the Dewey Decimal System. (Other libraries, including the Library of Congress, use other filing systems but Dewey is the most widely used.) The system divides book subjects into one of 10 numerical groups that are them subdivided further by specific subject. For example, 595.7 are books about insects.

Nearly all card catalogs used by libraries are now in digital form. While the structure of the listing remains the same with author, title and subject available, library patrons are now able to search by keyword, which could appear in any of the three listing categories. Digital card catalogs also allow users to see if the book is checked in or out, as well as which branches in a large library system hold the book.