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Library Classification

Library Classification

Library Classification or Classification or Book Classification or Bibliographic Classification is the process of arranging, grouping, coding, and organizing books and other library materials (e.g. serials, sound recordings, moving images, cartographic materials, manuscripts, computer files, e-resources etc.) on shelves or entries of a catalog, bibliography, and index according to their subject in a systematic, logical, and helpful order by way of assigning them call numbers using a library classification system, so that users can find them as quickly and easily as possible. The call number serves a dual purpose: it determines the place of a book on the shelf and colocates books on the same topic next to each other.

Call number consists of a class number providing class designation, a book number providing author representation, and a collection number denoting the collection to which it belongs. In ordinary classification, we deal with the arrangement of ideas and the objects in a systematic order. But in library classification, we are concerned with documents, and the aim is to arrange these in the most helpful and permanent order. Similar to knowledge classification systems, bibliographic classification systems group entities that are similar and related together typically arranged in a hierarchical tree-type structure (assuming non-faceted system; a faceted classification system allows the assignment of multiple classifications to an object, enabling the classifications to be ordered in multiple ways). It requires a detailed scheme of classification in which knowledge is divided into broad areas, which are again subdivided into subjects or main classes. Main classes are further divided into sub-classes, and sub-classes are divided into and divisions and so on. In this way classification proceeds from the general to the specific dividing and categorizing concepts into logically hierarchical classes based on the characteristics they have in common and those that distinguish them. Levels of hierarchy in the classification schedules are indicated by indentions. Each subject, classes, sub-classes, and its divisions are represented by a system of numerals or letters or a combination of both called Notation. It is this notation that helps in the arrangement of documents on the shelves. Classification provides a logical approach to the arrangement of documentary materials. Use of classification enables library users to browse on shelves to find its materials and also additional items on the same or related subjects, and, to find out what documents the library has on a certain subject. Library classification systems are one of the two methods used to facilitate subject access to library materials. The other is alphabetical indexing languages such as thesauri and subject headings list. Classification organizes knowledge and library materials into a systematic order according to their subject content, while subject headings provide access to documents through vocabulary terms. Thesauri or subject headings can assign multiple terms to the same document, but in classification, each document can only be placed in one class. So we can say that classification number assigned to a document using as library classification scheme provides an exact location for an item on the shelves. The cataloger assigns a classification, or call number, in correlation with the subject headings. Some of the popular classification systems are the Library of Congress Classification (LCC), the Dewey Decimal Classification (DDC) the Bliss Bibliographic Classification (BC), the Universal Decimal Classification (UDC), Cutter Expansive Classification, and the Colon Classification (CC); DDC and LCC being the most popular ones. DDC is the most widely used classification system throughout the world. LCC is highly enumerative by listing all subjects of the past, the present, and the anticipatable future and its notation is enormously hospitable and expandable. LCC is also the most continuously revised classification scheme. The Classification Web database of LCC is updated daily incorporating new additions and changes proposed by catalogers and approved by the editorial committee of LCC. In the United States, academic libraries generally use Library of Congress Classification and public and school libraries prefer to use the Dewey Decimal Classification. Major libraries now use web versions of LCC and DDC to classify their materials. The electronic version of LCC is available online as Classification Web ( and an electronic version of DDC is available online as WebDewey (

Janis L. Young and  Daniel N. Joudrey¹ describe Library Classification as below:

What is Classification?

  • The use of a system of notations or symbols to categorize the contents of resources
    • Used to provide logical shelf arrangement (i.e., call numbers), but also can be useful in searching the catalog
    • Organized by disciplines, they begin with broad general topics which give way to more specific subtopics

According to Joudrey, Taylor & Miller, classification is “the placing of subjects into categories.”

It is the process of determining where a resource fits within the classification’s structure, and then
assigning the notation that most closely approximates the aboutness of the resource.

Classification is more than finding the right notation or category; it is about relationships. It provides a logical arrangement of topics and subtopics from the general to the specific that can be translated into a linear arrangement for materials in a library. Classification traditionally provides formal, orderly access to the shelves, but it is also a mechanism by which to collocate materials in the catalog. It’s what makes browsing possible.

Principles of Library Classification

Library classification is a system of organizing library materials to facilitate their retrieval, use, and management. The principles of library classification are the fundamental rules and guidelines that govern the organization of library materials. Here are some of the key principles:

1. Clarity and consistency: The classification system should be clear and easy to understand, and should use consistent rules and principles.

2. Hierarchical organization: Materials should be arranged in a hierarchical order, with general categories at the top and specific subcategories at the bottom.

3. Logical organization: The classification system should reflect the logical relationships between subjects and topics.

4. Exhaustiveness: The system should be comprehensive enough to cover all possible subjects and topics, while also avoiding duplication and overlap.

5. Specificity: The system should allow for a precise and specific classification of materials.

6. Flexibility: The system should be flexible enough to accommodate changes and new additions to the collection.

7. Accessibility: The system should be designed to facilitate easy retrieval and use of materials by library users.

8. User-centered: The classification system should be designed with the needs of library users in mind, rather than the preferences of library staff or administrators.

Overall, the principles of library classification are aimed at making library materials more easily accessible and usable for library users, while also facilitating efficient management and organization of the library collection.

Another way of explaining the principles of library classification is given below:

Library classification is the process of organizing library resources systematically. The principles of library classification include:

1. Subject Approach: If classification helps in the use of books, a method of systematic arrangement is adopted, whether it is logical or not.

2. Porphyry’s Tree: Knowledge is totality, and classification starts from knowledge.

3. Extension and Intention: The classification should be based on the extension and intention of the subject.

4. Inductive and Deductive Nature of Classification: The classification should be based on both inductive and deductive methods.

5. Aristotelian Pattern: The classification should be based on the Aristotelian pattern of division.

6. Hierarchical Structure of Classification: The classification should be based on a hierarchical structure.

Principles of Library Classification According to the Classification and Shelflisting Manual of the Library of Congress Classification

The following principles of classification generally apply when classifying works according to the Library of Congress classification system²:
1. Subject. Class works according to their subject matter.
2. Topic vs. form. Unless instructions to the contrary are printed in the schedules, class a work by its specific subject, not by its form under a broader topic. Within a given topical area, class by subject, ignoring form unless form captions have been established under the subject. If no number for the specific form of the work being cataloged has been established in the schedules under the subject, see F 195, sec. 4.
3. Topic vs. place. Within a given topical area, if a choice must be made between classing by specific subject and classing by place, prefer classification by the subject, unless instructions to the contrary exist or unless precedent, as reflected in the shelflist, clearly indicates otherwise. If no clear precedent exists, record any decision to class by place rather than by subject by adding notes of the following type to the schedule:
Under the topical caption:
Class works limited to a specific geographic area in [...]
Under the caption "By region or country":
Including specific topics
4. Specificity. Use the most specific number available. Use a broader number only if no specific number is available and it is not feasible to establish one.
5. Multi-topic works. Where several subjects are discussed in a work, choose the classification number according to the most appropriate of the following principles:
Class according to instructions printed in the schedules.
Class according to dominant subject.
If no subject is dominant, class under the first one mentioned in the work being cataloged.
Class with a broader subject, if the work deals with several subjects that, taken together, constitute a major part of a larger subject.
6. Choosing among several appropriate class numbers.   In problematic cases where several numbers appear satisfactory, class according to the intent of the author or where it appears that the work would be most usefully located.
7. Influence of one subject on another. Unless instructions in the schedules or past practice dictate otherwise, class works on the influence of one subject on another with the subject influenced.
8. Relationship of class number with subject headings. For the relationship between the order of subject headings and the class number, see H 80.

  • Classification
  • Book Classification
  • Bibliographic Classification



1. Janis L. Young and  Daniel N. Joudrey, Library of Congress, "Library of Congress Subject Headings: Online Training," (accessed March 17, 2020).

2. Library of Congress Classification -- Classification and Shelflisting Manual — Classification — General — F 10 General Principles of Classification.


Article Title
  • Library Classification

Website Name
  • Librarianship Studies & Information Technology


Last Updated
  • 2023-03-29

Original Published Date
  • 2015-08-01