Classification Systems

Imagine this. You go to the library and the books are shelved in no particular order. Finding material on your research topic will not be easy. Let's say the books are organized by color. If you are searching for books on American History you will have to run all over the library, upstairs and downstairs, through all the stacks of books, because the books on American history may come in many colors. The blue books may be on the first floor while the yellow books are on the second floor. Don't laugh, at one time in history, long before Mr. Dewey, books were shelved by size and color. Although this system was efficient in terms of shelving, it is not very convenient or efficient for 'browsing' or for patron retrieval of library books. In those days, patrons were only allowed to use the card catalog, they were never permitted to go near the shelves to get books!

Most libraries today use classification systems based on the subject to organize materials. The two most popular classification systems are the Library of Congress and Dewey Decimal. Both provide detailed schemes or tables to assign call numbers to each book in the library collection. Call numbers are made up of a combination of letters and numbers.

For example, 973.3 G45, is the call number for a book about the American Revolution in one library collection. [973 is American history; .3 is the historical period that includes the Revolutionary Period; G45 is the author's identification number.] You can consider the call number as the address of the book in the library, and the address tells you exactly where to locate it.

Since these classification systems are based on subject matter, similar materials are shelved next to each other. This is both logical and convenient. As you look for a specific book, you can browse the other books shelved on either side. Browsing in this fashion is often helpful in the research process.

Follow this link to a table that outlines the Dewey Decimal Classification system. Select several of the category links and see how the subject areas are subdivided in the Dewey Decimal Classification Table.

Follow this link to an interactive table of the Library of Congress Classification System.