A subject heading is a term, a word, or a group of words that represents or expresses the subject content of a book, article, or other reading material. The books or articles on a given subject could be grouped under particular headings to make them easily accessible to readers because it is used in catalogs, bibliographies, and indexes. It expedites subject-wise entry arrangement and guarantees prompt availability of library materials collectively on a given subject by making them easily accessible to users and researchers.
Subject headings are frequently located at or close to the bottom of the page of an online record of a book or article, or on the page of a book that includes the publisher’s information.
Bold face type headings are the only approved headings for use as subject headings. Lightface type headings are not to be used as subject headings but only references may be made from them to such headings that may be used.
Example: Library science (May subdivision geog.) 020
UF-Librarianship
BT-Documentation Information Science
NT-Cataloguing
RT-Bibliography
Note: UF (Used for); BT (Boarder term); NT (Narrower term); RT (Bibliography)
Types of Subject Headings
There are three types of subject headings:
1. Library of Congress Subject Headings (LCSH)
Library of Congress Subject Headings (LCSH) is a list of headings produced from the subject authority file maintained by the United States Library of Congress for use in bibliographic records. It is commonly abbreviated as LCSH and sometimes used interchangeably with the phrase “subject authority file.”
The LCSH was first published between 1909 and 1914 in two volumes under the title Subject Headings in the Dictionary Catalogue of the Library of Congress. In 1975, the title was updated to Library of Congress Subject Headings in its eighth edition. The 14th edition of LCSH was published in three volumes in 1991 and is now updated annually with weekly updates. The 43rd edition, published in 2021, expanded to six large red volumes and contains approximately 11,993 scope note entries and 89,577 subject authority records, which include class numbers for easy cross-referencing with the Library of Congress Classification system.
link: https://id.loc.gov/authorities/subjects.html
2. Sears List of Subject Headings
The Sears List of Subject Headings supports the Dewey Decimal Classification scheme. It is a general-use controlled vocabulary designed to describe library collections, specifically geared toward smaller public and school libraries. The list includes topical, form, geographic headings, and proper names.
Minnie Earl Sears compiled her list of subject headings for small libraries in 1923, based on LCSH. In its sixth edition, published in 1950, the title changed to Sears List of Subject Headings. Subsequent editions (13th, 14th, 17th, 19th, and 23rd) were released in 1986, 1991, 2000, 2007, and 2022, respectively. The 23rd edition, published by H.W. Wilson in New York, consists of 950 pages.
link: https://www.hwwilsoninprint.com/pdf/sears_23_pr.pdf
3. Medical Subject Headings (MeSH)
Medical Subject Headings (MeSH) are a comprehensive, controlled vocabulary used to index books and journal articles in the life sciences.It serves as a thesaurus that facilitates effective searching and retrieval. MeSH was created and is regularly updated by the United States National Library of Medicine (NLM) and is utilized by the MEDLINE/PubMed article database.
The MeSH system was first introduced in 1960, containing about 4,400 terms to standardize medical vocabulary for indexing and retrieving information. The 1990 edition marked a significant expansion due to advancements in medical research. By the mid-1990s, MeSH transitioned to a digital format, integrating with databases such as PubMed for better access. The 2005 edition included updates in fields like genomics and biotechnology, while the 2022 edition introduced terms relevant to the COVID-19 pandemic and telemedicine. The latest edition (2024) features over 30,000 descriptors, reflecting current trends in medicine, including artificial intelligence in healthcare and personalized medicine.
Link: https://meshb.nlm.nih.gov/
Importance of Subject Heading
Subject headings play a crucial role in organizing information in libraries, databases, and other information systems. They enhance the accessibility, discoverability, and overall usability of resources. Here are some key reasons why subject headings are important:
1. Improved Search ability:
Subject headings provide a consistent method for categorizing and describing topics, which helps users easily find relevant materials. By standardizing terms, they reduce confusion caused by synonyms, variations, or jargon. Users can retrieve all materials on a specific subject by searching for the designated subject heading.
2. Efficient Organization of Resources:
Subject headings enable libraries and databases to systematically organize large volumes of resources. This structure makes it easier for users to browse topics and discover related materials. For instance, all books on “Environmental Policy” will be grouped under that heading, allowing users to find all related works, regardless of their titles.
3. Consistency across Systems:
Subject headings ensure uniformity in how information is indexed across various platforms (libraries, databases, catalogs). This consistency allows users to search multiple systems and still find relevant results. For example, the Library of Congress Subject Headings (LCSH) is widely used by libraries globally, ensuring similar search outcomes across different institutions.
4. Facilitates Browsing:
Subject headings enable users to browse categories systematically. Users who may not know specific titles or authors can explore headings to discover a wide range of resources on a subject. By following a hierarchy from broad to specific terms, users can refine their searches and uncover more targeted resources.
5. Disambiguation:
Many words have multiple meanings and can be used in different contexts. Subject headings help clarify these terms by providing specific context. For example, the word “Bass” can refer to either a type of fish or a musical instrument. Subject headings such as “Bass (Fish)” and “Bass (Musical Instrument)” specify the intended meaning.
6. Access to Related Topics:
Through cross-references and related terms, subject headings help users discover topics they might not have initially considered. For instance, if someone searches for “Global Warming,” the system may guide them to related subjects such as “Climate Change” or “Greenhouse Effect.”
7. Multilingual and Multidisciplinary Access:
Subject headings can provide access across languages and disciplines. In some systems, they are translated into multiple languages or cover topics from various fields, making information more accessible to a diverse range of users.
8. Precision in Academic and Research Contexts:
In academic research, subject headings provide precision, ensuring that researchers can find scholarly materials relevant to their specific area of study. This is particularly crucial in fields like medicine (using MeSH) or law, where specificity is vital. For example, researchers searching for “Public Health Policy—United States—21st Century” will find highly relevant materials without sifting through unrelated works.
9. Time and Resource Efficiency:
By grouping similar materials under specific headings, subject headings save time for both users and librarians. Users can quickly navigate to the subject heading that fits their interest, rather than searching through countless unrelated records.
10. Support for Subject Authority Control:
Subject headings are essential for authority control, which helps maintain the quality and consistency of information retrieval. By using standardized headings, systems prevent term duplication or the fragmentation of records across various subject variants. For example, all works on “Mental Health” will be listed under a single heading, avoiding categorization under different terms like “Mental Illness” or “Psychiatric Health.”
11. Enhances information retrieval for different user levels:
Subject headings cater to both novice and expert users. Beginners may benefit from broader headings, while more advanced users can drill down to specific subheadings for in-depth research.
Subject headings are essential for efficiently arranging and classifying information so that users can find pertinent content more quickly. They guarantee consistency between databases and catalogs by employing standardized terminology, which enhances the discoverability of resources. Subject headings, in general, improve information retrieval by facilitating access to particular subjects, places, or types of content for both researchers and casual users.