The Library of Congress Online Catalog contains approximately 14 million records representing books, serials, computer files, manuscripts, cartographic materials, music, sound recordings, and visual materials. The Online Catalog also displays searching aids for users, such as cross-references and scope notes. The catalog records reside in a single integrated database; they are not separated according to type of material, language of material, date of cataloging, or processing/circulation status.
As an integrated database, the Online Catalog includes 3.2 million catalog records from an earlier database. These catalog records, primarily for books and serials cataloged between 1898 and 1980, are being edited to comply with current cataloging standards and to reflect contemporary language and usage. The legend "[from old catalog]" indicates that the headings may deviate from current Library of Congress cataloging policy. For a complete search of books and serials cataloged prior to 1980, researchers onsite at the Library should also use the Main Card Catalog.