Libraries used 'controlled vocabulary' or standardized terms to classify books and articles. In general, college libraries use the Library of Congress (LC) classification system, which includes a standard set of subject terms for items. When you look at a book, the subject headings are hyperlinked so that you can find other books in your subject.
The Library of Congress classification system includes 100,000+ subject headings. They range from very general (ex. Art) to very specific (ex. Art -- Political aspects -- United States -- History -- 20th century). Subject headings may contain subdivisions, separated by a double hyphen (--) to narrows down to specific parameters.
You do not need to know the correct subject heading to use them effectively. Simply find a relevant resource, scan the subject headings, and click on the subject heading(s) that are relevant to your search. See the example on the right.
In a hypothetical research paper, I'm looking for books about how art & literature were used to advance American objectives in the Cold War. When I scroll down this record, I see 'Library of Congress Subject Headings' (see screenshot). Some are general, but others are specific.
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One of the subject headings matches what I'm looking for: Art Political aspects United States History 20th century. The subject headings are hyperlinked so I can search all books, articles, videos, and more that are classified under the same heading.
