Libraries use classification systems to organize the books on the shelves. A classification system uses letters and/or numbers (call numbers) to arrange the books so that books on the same topic are together. This arrangement results in "serendipitous browsing": you find one book in the catalog, go to the shelf, and an even better book is sitting right next to it.
Libraries in the United States generally use either the Library of Congress Classification System (LC) or the Dewey Decimal Classification System (DDC) to organize their books. Most academic libraries use LC, and most public libraries and K-12 school libaries use Dewey. Here at Napa Valley College, we use the Dewey system, but at neighboring Solano College, they use the Library of Congress.
How is the Dewey Decimal Classification System (DDC) arranged?
The DDC has ten major classes:
Computer science, information & general works
300 Social Sciences
500 Natural Sciences/Mathematics
700 The Arts
Think of the decimal system as 10's, 100's and 1000's. Think of information as first classified into 10 main classes, then these 10 classes broken down into 100 divisions, and these 100 divisions broken down into 1000 sections:
The picture below depicts the main classes and some selected subdivisions:
Looking at the book's call number:
A book's call number is similar to its address: it is where the book can be found on the shelf. Here's an example of a book's call number:
796.334 Book title: Coaching Girls' Soccer
DEW Author: John DeWitt
Call Number: 796.334 DEW
The first line describes the subject of the book, sports, which is broken down as this:
796 = Athletic and outdoor sports games
.3 = Ball games
.34 = Inflated ball driven by foot
The second line represents the first three letters of the author's last name:
DEW = DeWitt
For more in-depth information on the Dewey Decimal system, check out OCLC's excellent description of the classification system.
To gain a fascinating glimpse into Melvil Dewey, the creator of the Dewey Decimal System, read Sarah Prescott's wonderful article,"If You Knew Dewey."
Locating Circulating Books
To find circulating books, take the link to the Solano, Napa and Partners' (SNAP) online catalog. You can search by keyword, title, author or series.
Library of Congress Subject Headings
What is a Subject Heading?
The Library of Congress Subject Headings (LCSH) provides an alphabetical listing of authorized or preferred terms established by the Library of Congress since 1898. These "official" terms should be used when doing subject searches in the Napa Valley College SNAP online catalog.
There are basically two ways to search for information on a topic: using keywords from the title or information about the item, and using subject headings.
While keyword searching relies on the language used by the author, the publisher, or the person writing the abstract or summary, subject headings use a single word or phrase to represent a particular topic or concept. For example, the terms substance abuse, chemical dependency and addiction are all used to describe the same concept, but only one of them will be used as the subject heading.
This makes subject headings a very powerful way to search for information on a topic because once you know the subject heading, you can search for everything on the topic regardless of the language used in the title or other information about the book.
Scientific Information Literacy Modules
Unit 1: What is Science?
Unit 2: Scientific Information
Unit 3: Information Formats
Unit 4: Defining Search Terms
Unit 5: Conducting a Literature Review
Unit 6: Science Information Sources
History Information Literacy Modules
copyright 2011 Napa Valley College
updated June 14, 2011, by Nancy McEnery, Reference Librarian-Instructor