How to organize books using the Dewey Decimal System?

The Dewey Decimal System (DDC) is a widely adopted method for organizing library materials, primarily non-fiction books, by subject. It assigns a unique numerical code, known as a call number, to each book, ensuring that materials on similar topics are grouped together for easy discovery and retrieval.

Understanding the Dewey Decimal System

Developed by Melvil Dewey, the DDC systematically divides all human knowledge into ten main categories. These categories are further subdivided using decimals to represent increasingly specific topics. This hierarchical structure allows for a precise and logical arrangement of books on shelves.

The Ten Main Classes of the DDC

The DDC's foundation lies in its ten primary classes, each covering a broad subject area:

Main Class	Range	Subject Area
000s	000-099	Computer Science, Information & General Works
100s	100-199	Philosophy & Psychology
200s	200-299	Religion
300s	300-399	Social Sciences
400s	400-499	Language
500s	500-599	Natural Sciences & Mathematics
600s	600-699	Technology (Applied Sciences)
700s	700-799	Arts & Recreation
800s	800-899	Literature
900s	900-999	History & Geography

For more detailed information, the OCLC Dewey Decimal Classification website offers comprehensive resources.

Decoding Dewey Decimal Call Numbers

A complete Dewey Decimal call number typically comprises two main components: the classification number (the Dewey number) and the Cutter number.

The Dewey Number

This is the numerical part that classifies the book by subject. It starts with a three-digit number representing a main class, followed by a decimal point and additional digits to denote narrower subjects.

Example: A book about specific insect species, like butterflies, might have a Dewey number starting with 595.78.
- 500s indicates Natural Sciences.
- 590s narrows it down to Zoology.
- 595 focuses on Insects.
- 595.7 specifies certain insect orders.
- 595.78 pinpoints Lepidoptera (butterflies and moths).

The Cutter Number

Following the Dewey number, the Cutter number further arranges books alphabetically by author within the same subject classification. It usually consists of a letter (often the first letter of the author's last name) followed by one or more numbers.

Example: A book on butterflies by an author named "Broch" might have a full call number like 595.789 BROC.

Special Handling for Biographies

While the standard DDC allocates the 920s and 921 for biographies, some collections may use an alternative system for enhanced clarity. For instance, biographies might be labeled with the letter "B" instead of the numerical 921, followed by a Cutter number that could represent the biographee or the author. This modification allows for streamlined organization of biographical works in those specific collections.

How to Organize Books Step-by-Step

Organizing books using the Dewey Decimal System requires careful attention to the call numbers and their sequence.

Locate the Call Number: Find the complete call number, including both the Dewey number and the Cutter number, typically printed on the spine of each book.
Sort by Main Class: Begin by grouping books according to their initial three-digit main class number (e.g., all books in the 000s together, then all 100s, and so on).
Sort by Decimal (Digit by Digit): Within each main class, sort books numerically by the digits before the decimal point. Then, for numbers with decimals, it's crucial to file digit by digit, not by whole number. This means that 595.0123 would come before 595.789, which in turn would be shelved before 595.9. Treat the numbers after the decimal point as continuous expansions of the subject.
- Correct Filing Order Example:
  - 595.01
  - 595.0123
  - 595.7
  - 595.789
  - 595.9
  - 596
Sort by Cutter Number: After the full Dewey number is correctly sequenced, arrange books alphabetically by the letter in the Cutter number, and then numerically by the digits that follow the letter.
- Example: 595.789 BROC would be placed before 595.789 SMIT.
Final Placement: Once sorted by both the Dewey and Cutter numbers, books on the exact same topic by the same author will be grouped together. If there are multiple copies of the same book, they are typically shelved consecutively, often labeled with "c.1," "c.2," etc.

Practical Tips for Efficient Book Arrangement

Clear Labeling: Ensure that all books have clear, durable labels displaying their complete call numbers for easy identification.
Regular Shelf Reading: Periodically review your shelves to confirm that books are in their correct order. This practice is essential for maintaining the system's accuracy.
Allow for Expansion: Always leave some empty space at the end of each shelf or section. This prevents the need to reshuffle large sections when new books are added.
Understand Local Variations: Be aware that some libraries or personal collections might implement minor adaptations to the DDC, such as using "B" for biographies instead of 921, or incorporating publication dates into call numbers for finer distinctions. Always adhere to the specific guidelines of the collection you are organizing.