Library numbers, more commonly known as call numbers, are unique alphanumeric codes used by libraries to organize books and other materials on their shelves. They act like an address, guiding you to the exact location of a specific item.
What Are Library Numbers (Call Numbers)?
A call number is a unique identification mark assigned to each item in a library's collection. Instead of simply listing books alphabetically by title, libraries use these numbers to arrange materials by subject, then by author, and sometimes by publication date. This systematic approach allows for efficient browsing and retrieval, grouping similar topics together.
The Anatomy of a Call Number
Call numbers are typically read from top to bottom, then left to right, and each section provides specific information about the item. While specific formats vary slightly between different classification systems, the core components remain consistent:
Subject Classification
The initial sections of the call number, often consisting of letters and numbers, represent the subject of the book. This is the primary way libraries group related materials. For example, all books on biology might start with a specific number range or letter sequence, allowing you to find them together on the shelf.
Author Identification
Following the subject classification, a letter-and-decimal section typically represents the author's last name. This part, often called the "cutter number" or "book number," helps to arrange books by the same author (or about the same topic by different authors) alphabetically within a given subject category. This ensures that if a library has multiple books on the same subject by different authors, they are organized in a logical sequence.
Publication Date
The last section of a call number is often the date of publication. Including the year helps distinguish between different editions of the same book or different works by the same author published at various times, ensuring you can locate the most current or specific edition you need.
Here's a summary of the common call number components:
| Component | Purpose | Example (LCC) | Example (DDC) |
|---|---|---|---|
| Subject Section | Classifies the item by its main topic. | QL 737 | 599.5 |
| Author Section | Organizes items alphabetically by author within a subject. | D48 | D48 |
| Publication Date | Differentiates between editions or versions. | 2018 | 2018 |
Major Classification Systems
The two most widely used systems for creating library numbers are the Library of Congress Classification (LCC) and the Dewey Decimal Classification (DDC).
Dewey Decimal Classification (DDC)
The Dewey Decimal Classification (DDC) system is primarily used in public libraries and school libraries. It divides all knowledge into ten main classes, each represented by a three-digit number, with decimals used for further subdivisions.
- Example Call Number:
599.5 D48 2018500: Natural Sciences and Mathematics590: Zoology599: Mammals599.5: Cetaceans (whales, dolphins)D48: Represents the author (e.g., Davidson)2018: Year of publication
Library of Congress Classification (LCC)
The Library of Congress Classification (LCC) system is more detailed and is primarily used by academic and research libraries. It uses a combination of letters and numbers to denote subjects.
- Example Call Number:
QL 737 .C4 D48 2018QL: ZoologyQL 737: MammalsQL 737 .C4: Cetacea (whales, dolphins).D48: Represents the author (e.g., Davidson)2018: Year of publication
Why Are Call Numbers Important?
Library call numbers are fundamental to effective library operation and user experience:
- Efficient Organization: They provide a systematic way to arrange vast collections, making it easy to put books back in their correct place after use.
- Easy Retrieval: By knowing a book's call number, you can quickly navigate to its exact spot on the shelf, even among millions of items.
- Subject Browsing: Call numbers group books on similar topics together, allowing patrons to browse shelves and discover related materials they might not have initially searched for.
- Inventory Management: They assist librarians in tracking the library's holdings and managing their extensive collections.
Understanding how library numbers work empowers you to navigate any library with confidence, efficiently finding the resources you need.
