Library of Congress Subject Headings

The Library of Congress Subject Headings (LCSH) comprise a thesaurus (in the information science sense, a controlled vocabulary) of subject headings, maintained by the United States Library of Congress, for use in bibliographic records. LC Subject Headings are an integral part of bibliographic control, which is the function by which libraries collect, organize, and disseminate documents. It was first published in 1898, a year after the publication of Library of Congress Classification (1897). The last print edition was published in 2016. Access to the continuously revised vocabulary is now available via subscription and free services. Subject headings are normally applied to every item within a library's collection and facilitate a user's access to items in the catalog that pertain to similar subject matter, in order to save time finding items of related subject matter. Only searching for items by 'title' or other descriptive fields, such as 'author' or 'publisher', would take more time and potentially miss locating many items because of the ineffective and inefficient search capability. An art and a science Subject heading is a human and intellectual endeavor, by which trained professionals apply topic descriptions to items in their collections. Without a uniform standard, each library might choose to categorize the subject matter of their items differently. The widespread use and acceptance of the Library of Congress Subject Headings facilitates the uniform access to and retrieval of items in libraries across the world; users can use the same search strategy and LCSH thesaurus, if the correct headings have been applied to the item by the library. Some LCSH decisions are achieved by extensive debate and even controversy in the library community. LCSH is the world's most widely used subject vocabulary. Despite LCSH's wide-ranging and comprehensive scope, libraries that deal with more specific types of collections or user communities may use other vocabularies; for example, many medical libraries in the United States use the National Library of Medicine's Medical Subject Headings (MeSH).