Purpose: Search citations with terms tagged with specific subjects related to the article
Before discussing the concept of "subject headings," first, it is important to understand what a resource record is. A resource record provides information about the resource, such as who wrote or edited the resource, the year of publication, the title, the publisher, an abstract, subject headings, physical descriptions, publications numbers, and sometimes more. This is what appears on the screen after you click on the title of a journal article in a database and is pictured on the screen in the example further down in this page.
Subject headings are specific words associated with resources, including articles. The subject headings are specific words called controlled vocabulary and is determined by the Library of Congress or by the creators of a database. A resource record is assigned with a subject heading so that when people browse topics based on a specific subject category, that specific citation is included in the results.
For instance, if an author writes an article about piano music, the official subject heading for piano music is used, which is Piano in the Music Index database, and the subject term is attached to that resource. As a result, when a subject search for Piano is conducted, that article will appear in the search. This is similar to using a hashtag in social media. Please find below a subject search in Music Index for piano. I chose a particular article from my subject search with the word Piano to demonstrate the subjects terms attached to this article: