Dewey Decimal classification

From WikiEducator
Jump to: navigation, search

Library Classification

Librarianship involves the selection, acquisition, organization and dissemination of information and knowledge available in various forms. The information available is immense and increasing, but not necessarily usable. In order to make the information retrievable and usable, the various sources of information need to be organized in a library. The larger the number of unorganized library holdings, more difficult to locate the needed document. Librarians address this issue with the help of classification.

According to Dr. Ranganathan, Library Classification is "the translation of the name of the subject of a book into preferred artificial language of ordinal numbers, which represent some features of the books other than their thought content”. In succinct, a library classification is a system of coding and organizing library materials (books, serials, audiovisual materials, computer files, maps, manuscripts, realia) according to their subject and allocating a call number to each information resource. The aim of Library Classification is to arrange the documents in the most helpful sequence.

Libraries adopted different practices to organize their collections. Some shelved materials by when the items arrived in the library. Others organized their collections by size or color of the book. Few others organized by author, by title, and/or by subject. Among all the arrangements, organizing library collections according to subject found helpful to users. Subject arrangement on the shelves is more convenient to users since items on the same subject are collated together. However, this subject arrangement should be based on sound principles and established plans and systems that can be consulted by Library and Information Service professionals for intellectual organization of information. Consequently, various classification systems have been devised to serve as the reference tools for organizing information, thereby, facilitating easy access and retrieval.

Classification Schemes

A classification system (scheme) as an established information processing and retrieval tool divides the “universe of knowledge” into various categories and subcategories in a hierarchical manner. Each category represents a class and each subcategory a division and/or subdivision. The division of knowledge proceeds from general classes to more and more specific subdivisions. In a classification scheme each class and subdivision is assigned with a specific symbol (class number), so as to assure that documents on the same subject are always classified under that symbol. Symbols used are numbers, letters, or a combination of letters and numbers, which may vary with the classification system used. The Dewey Decimal Classification is a numeric ordering system, whereas the Colon Classification is an alphanumeric system.

According to Margaret Mann, “a system for classification of books is a schedule, which maps out the field of knowledge in ways that are suitable for library purposes; main classes are followed by divisions and subdivisions of these classes; are gradation of subject is so arranged that specific subjects grow out of general subjects”. According to SR Ranganathan, classification scheme is “a scheme of classes fitted with terminology and notation”. A library classification system aids a classifier in ordering of the universe of knowledge such that books of similar subjects can be kept together on the shelves, assigning a unique shelf address (call number) to each document procured. Classification systems are designed to give a numerical, or alphanumerical notation to each item in the library. This notation is designed to indicate the subject matter of the item being classified.

The first practical universal classification schemes were developed in the late-nineteenth-century as a response to the problem of organizing libraries in the context of rapidly growing knowledge and an increase in the numbers of printed books. Universal schemes aim to be both comprehensive and also to expand and contract to fit the state of knowledge at any time. The most widely used universal classification schemes are the Dewey Decimal Classification (DDC), the Colon Classification (CC) the Universal Decimal Classification (UDC) and the classification scheme devised by the Library of Congress (LCC).

Dewey Decimal Classification

DDC is the most widely used classification system in the world. DDC is a general knowledge organization tool that is continuously revised to keep pace with knowledge. It provides a logical system for organizing every item in a library’s collection. Melvil Dewey conceived Dewey Decimal Classification system (DDC) in 1873, which was first published in 1876.

Editions and Formats

Now in its 22nd edition, DDC is available in print and Web versions. Dewey is also used for other purposes, example as a browsing mechanism for resources on the Web. The DDC has been translated into more than thirty languages. Translations of the latest full and abridged editions of the DDC are completed, planned, or underway in Arabic, Chinese, French, German, Greek, Hebrew, Icelandic, Italian, Korean, Norwegian, Russian, Spanish and Vietnamese.

First Edition

The first edition of DDC was published anonymously in 1876 under the title "A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library". It comprised of 42 pages, among which 11 pages were schedules and 18 pages were index. It included schedules to 1,000 divisions numbered 000–999, together with a relative index and prefatory matter. The major significance of this edition was that it was simple to work with and provided systematic arrangement of the materials in a library on the basis of subject approach.

Second Edition

The second, revised and greatly enlarged edition was published under Dewey’s name in 1885. The second edition entitled, “Decimal Classification and Relative Index,” appeared in 1885. This was eleven times voluminous than the first edition. It contained many changes. Since then 20 full editions and 14 abridgments have appeared.

The 21st edition of the DDC and Dewey for Windows published in 1996, making it the first time print and electronic formats are published simultaneously. It displayed the continuous revitalization efforts that have kept it contemporary throughout the twentieth century. Progress in science, technology, and even thought and culture was consistently reflected within the classification.

In 2002, WebDewey and Abridged WebDewey were published. DDC22 published in mid-2003, includes many new features that make the classification easier to use. DDC22 is the culmination of the work of editors, the Decimal Classification Editorial Policy Committee (EPC), and many advisors representing various fields and specific constituencies. Edition 22 reflects current thought in knowledge organization, and incorporates updates and changes identified during the use of 21st edition.

Edition 22

The 22nd edition reflects improvements in terminology in geographic area, law, political parties, language, literature and historical periods. Two striking changes in Edition 22, the removal of Table 7 and the streamlining of the Manual, have been motivated by a desire to promote classifier efficiency. Table 7 is removed and replaced with direct use of notation already available in the schedules and in notation 08 from Table 1. Information easily accommodated in notes in the tables and schedules has been transferred from the Manual, and redundant information already in the schedules and tables has been eliminated from the Manual. The remaining Manual entries are revised in a consistent style to promote quick understanding and efficient use.

The print version of the DDC 22 consists of the following four volumes:

  • Volume 1 comprises of introductory matter, the manual, auxiliary tables, and lists of relocations, discontinuations and reused numbers etc.
  • Volume 2 enumerates the 3 summaries and embeds the hierarchical notations from 000–599.
  • Volume 3 embeds the notations 600–999 to organize knowledge related to technology, arts, literature and geography.
  • Volume 4, the relative index lists the concepts alphabetically.


Web Dewey gives access to an enhanced version of the DDC22 database on the Web. WebDewey is part of the OCLC suite of cataloguing and metadata services. WebDewey offers easy-to-use, World Wide Web-based access to the Dewey Decimal Classification (DDC) and related information, with searching and browsing capabilities; Library of Congress Subject Headings (LCSH) intellectually and statistically mapped to Dewey numbers; and links from the mapped LCSH to the corresponding LCSH authority records.

WebDewey and Abridged WebDewey, the electronic versions of the full and abridged editions, respectively, are updated frequently and contain additional index entries and mapped vocabulary. The electronic versions and supplemental Web postings are the chief sources of ongoing updates to the DDC. On OCLC’s Dewey Website, selected new numbers and changes to the DDC are posted monthly, and mappings between selected new Library of Congress Subject Headings (LCSH) and Dewey numbers are posted biweekly.


In DDC, basic classes are organized by disciplines or fields of study. At the broadest level, the DDC is divided into ten main classes, which together cover the entire world of knowledge. Each main class is further divided into ten divisions, and each division into ten sections (not all the numbers for the divisions and sections have been used).

DDC Summaries

The main structure of the DDC is presented in the DDC Summaries following the introduction. DDC22 provides three summaries, showing successively the 10 main classes (first summary), the 100 divisions (second summary), and the 1,000 sections (third summary) of the basic scheme. Each class consists of a group of related disciplines.

First Summary - Ten Main Classes

The first summary contains the ten main classes. The first digit in each three-digit number represents the main class. The ten main classes are: 000 Computer Science, information & general works 100 Philosophy & psychology 200 Religion 300 Social Sciences 400 Languages 500 Science 600 Technology 700 Arts & recreation 800 Literature 900 History & geography

  • Class 000 is the most general class, and is used for works not limited to any one specific discipline, example, encyclopedias, newspapers, general periodicals. This class is also used for certain specialized disciplines that deal with knowledge and information, example, computer science, library and information science, journalism. Each of the other main classes (100-900) comprises a major discipline or group of related disciplines.
  • Class 100 covers philosophy, paranormal phenomena, and psychology.
  • Class 200 is devoted to religion. Both philosophy and religion deal with the ultimate nature of existence and relationships, but religion treats these topics within the context of revelation, deity, and worship.
  • Class 300 covers the social sciences. Class 300 includes sociology, anthropology, statistics, political science, economics, law, public administration, social problems and services, education, commerce, communications, transportation, and customs.
  • Class 400 comprises language, linguistics, and specific languages. Literature, which is arranged by language, is found in 800.
  • Class 500 is devoted to natural sciences and mathematics. Natural sciences (500) describe and attempt to explain the world in which we live.
  • Class 600 is technology. Technology consists of utilizing the sciences to harness the natural world and its resources for the benefits of humankind.
  • Class 700 covers the arts: art in general, fine and decorative arts, music, and performing arts. Recreation, including sports and games, is also classed in 700.
  • Class 800 covers literature, and includes rhetoric, prose, poetry, drama, etc. Folk literature is classed with customs in 300.
  • Class 900 is devoted to history and geography. When a work is a story of events that have transpired or an account of existing conditions in a particular place or region, it is classed in 900. A history of a specific subject is classed with the subject.

There are ten and only ten main classes in DDC. There is no change in the number ever since the publication of the first edition of the scheme. Each of the classes has ten divisions. These divisions are further divided − and then further divided. Each division becomes more specific. The more the numbers, the more specific the subject is. In this way, the Dewey classification system progresses from the general to the specific. The decimal place is used to make the number even more specific.

Second Summary – Hundred Divisions

Each of the main class in the First Summary is further divided into 10 divisions. Thus, the second summary contains the hundred divisions. The second digit in each three-digit number indicates the division. For example, 600 is used for general works on technology, 610 for medicine and health, 620 for engineering, 630 for agriculture.

Let us take the main class 700 Fine Arts and its second summary (10 x 10) 100 divisions. Each division is also represented by three digited numbers, wherein the last digit is always a zero, which indicates the absence of a section. 700 Fine Arts 710 Civic and landscape art 720 Architecture 730 Sculpture 740 Drawing, decorative arts 750 Painting 760 Graphic arts 770 Photography 780 Music 790 Recreational and performing arts - cinema, theatre, indoor games, sports.

The numbers of the divisions are to be treated as 'decimal numbers' as in the case of the main classes. We should presume that there is a dot before each number. For example, 790 should be spelt as seven, nine, zero but not as five hundred ninety.

Third Summary – Thousand Sections

Each of the 100 divisions is separated again into 10 sections. Thus, the third summary contains the thousand sections. Let us take the division 790 – Recreational activities in general. The section number is also a three digited one, wherein all are substantive digits. 790 Recreational activities in general 791 Entertainment – circuses, cinema, radio, television 792 Theatre 793 Indoor games, puzzles, dancing etc. 794 Indoor games of skill – chess, snooker 795 Games of change, card games 796 Ball games, athletics, walking, climbing, combat sports, ice and snow sports 797 Aquatic and air sports – boating, swimming, gliding, sky diving 798 Horsemanship and horse racing 799 Fishing, hunting, shooting.

The numbers of the sections are also to be treated as ‘decimal numbers’ as in the case of main classes and divisions. Hence, the number 799 should be spelt as seven nine nine.


A basic principle of DDC is it is arranged by discipline and not by subject; notation used is the pure notation and structural and notational hierarchy are maintained throughout the schedules. Indo-Arabic numerals are used to represent the class numbers. The first digit in each three-digit number represents the main class. The second digit in each three-digit number indicates the division. The third digit in each three-digit number indicates the section. The DDC uses the convention that no number should have fewer than three digits; zeros are used to fill out numbers. The notation of DDC schedule is made up of three basic numbers, which represent a particular place in the schedules. The first digit indicates one of the ten main classes. The second digit represents one of the ten divisions within the class. The third digit distinguishes one of the ten sections. Most notations require further refinements, so a decimal is inserted following this three-part number to be followed by more digits representing a specific element of the topic. The notation of a class varies with the depth of the discipline. If the extension of a discipline is more, the class number will be short. If the intention is more, the class number will be long.

Decimal Fractions

All the decimal fractions follow a whole number preceded by a decimal point, as an indicator. For example in 10.5, read as ten point five, 5 is a decimal fraction and is preceded by a decimal point. Similarly 0.92 is read as zero point nine two or simply as decimal nine two. The decimal fractions have constant place value of the digits. If we add any digit to the right end of any decimal fraction, the place value of the already present figures does not change. For example, if a decimal fraction 52 is extended by 5 to make it 525, the original place value of the first two digits, viz., 52 remains unaltered. This is due to the fact that every digit in a decimal fraction has its fixed absolute value irrespective of the total number of digits in a decimal sum. This property is the reverse of what it is in the whole numbers. In any classification system the number or symbols used to denote subjects have only ordinal value. They do not possess any cardinal value. The digits used in DDC are also devoid of any measure or weight or power or quantity. They only indicate their sequential value, that is, which number is to come earlier and which later. In DDC, of the two subjects denoted by numbers, say 935 and 954, it never means that the later is of any more value or importance than the former or vice versa. It only indicates that on the library shelves the book bearing the class number 954 will come after that of 953 and so on. When 511 will come earlier than 512 on the shelves, it does not indicate any of less value than 512 and by the same rule, 45 will come earlier than 5 and 301 earlier than 92 on the shelves.

Use of Decimal Point A decimal point or dot is inserted between the third and fourth digits of the complete number. The dot is not a decimal point in the mathematical sense, but a psychological pause to break the monotony of numerical digits and to ease the transcription and copying of the class number. Educational psychologists believe that 324.12 is more easily remembered than 32412. Hence, this dot has no function other than to reinforce memory.

Relative Index

The “relative” index is so called because it is claimed to show relationships of each specific topic to one or more disciplines and to other topics. It contains terms found in the schedules and tables, and synonyms for those terms; names of countries, states, provinces, major cities, and important geographic features; and some names of persons. The DDC relative index enumerates alphabetically all the main headings in the classification schedules, plus certain other specific entries not actually listed in the schedules. The classifier should consult the index, especially in cases in which the location of the desired topic, or the precise nature of its relation to other topics, is in doubt. Yet the relative index should never become a substitute for the schedules. Since the primary arrangement of knowledge is by discipline, any specific topic may appear in any number of disciplines. Various aspects of such a topic are usually brought together in the relative index.


Notes supply information that is not obvious in the notational hierarchy or in the heading with regard to order, structure, subordination, and other matters. Notes may appear in the record for a number or a span of numbers. Notes may also appear at the beginning of a table. Footnotes are used for instructions that apply to multiple subdivisions of a class, or to a topic within a class. Individual entries in the Manual are also considered notes.

Notes in the schedules and tables generally appear in the following order: revision, former-heading, definition, number-built, standard-subdivisions-are added, variant-name, scope, including, class-here, arrange, add (including subdivisions-are-added), build, preference, discontinued, relocation, class-elsewhere, see-reference, see-also reference, see-Manual, and option notes. All these types of notes can be grouped in 3 categories:

  1. Notes that describe what is found in a class;
  2. Including notes (notes that identify topics in standing room); and
  3. Notes that describe what is found in other classes; (iv) Notes that explain changes or irregularities in the Schedules and Tables.


Auxiliary tables 1 through 6, found in volume 1 of DDC22, give the classifier one way to expand existing numbers in the schedules. Each number in these tables is preceded by a dash to show that it cannot stand alone as a classification number i.e., never used as a class number but attached to the class numbers (000–999) taken from the schedule. The dash should be omitted when the number is attached to a class notation. The tables in the DDC 22 are: Table 1 : Standard subdivisions Table 2 : Geographic Areas, Historical periods, Persons Table 3 : Subdivision for the Arts, for Individual Literature, for Specific Literary Forms T3A Subdivisions for Works by or about Individual Authors T3B Subdivisions for Works by or about More than One Author T3C Notation to Be Added Where Instructed in Table 3B, 700.4, 791.4, 808 -809 Table 4 : Subdivision of Individual Language and Language Families Table 5 : Ethnic and National groups Table 6 : Languages. Table numbers are given in full in the number column of the tables, and are never used alone. Except for notation from Table 1 (which may be added to any number unless there is an instruction in the schedules or tables to the contrary), notations from the tables are added only as instructed in the schedules and tables. Number building with the aid of notations from the Tables is discussed in detail in the subsequent chapters.

Number Building

Content to be added.