ABSTRACT
A library catalog is never complete because the library collection is a living institution. Materials listed in the catalog represent everything the library owns, plus collections from other libraries in the case of a shared catalog. Included in the catalogs are books, periodicals, pamphlets, audiovisual materials, computer files, and digital information. In the nineteenth and twentieth centuries, the card catalog became widely accepted and almost completely replaced the book catalog. The card catalog system offers flexibility. Cards may be removed easily from the catalog to reflect changing status, such as withdrawal or loss of the item. Online public access catalog offers fast retrieval and an immediate display. In a shared online catalog, users can retrieve information from other participating libraries. These systems not only indicate the holdings of different libraries but also tell the circulation status of an item, when the item is due back.
