OnlineKatalogs

OnlineKatalogs are web-based catalogs that provide searchable access to the holdings of libraries, archives, museums, and some retailers. They aggregate metadata about items such as books, journals, digital objects, and media, enabling users to discover items, check availability, and locate physical or digital copies.

In libraries, an OnlineKatalog often forms the public interface to an integrated library system (ILS) or a separate discovery layer. Users can search by title, author, subject, ISBN, or keyword, and refine results using facets such as format, language, year, and location. Records display holdings, shelf locations, item status, and access to digital copies; services may include placing holds, requesting interlibrary loan, and linking to full text or external catalogs.

Data and standards: catalogs rely on metadata standards such as MARC 21 and Dublin Core; FRBR concepts influence how works, expressions, and items are modeled; authority data helps disambiguate authors and subjects. Modern OnlineKatalogs increasingly use linked data approaches (e.g., BIBFRAME) and expose APIs or protocols like Z39.50, SRU/SRW, and OpenURL for interoperability and integration with other systems and discovery services.

History and scope: from manual card catalogs to automated online catalogs; many libraries employ discovery layers that combine catalog data with indexes for journals and digital repositories. Some institutions maintain retail or institutional catalogs with similar interfaces for products or archival assets.

Challenges include data quality and completeness, coverage gaps, and the need for ongoing metadata maintenance; user experience considerations, accessibility, and authentication for restricted resources; and the balancing of local catalog data with centralized catalogs such as union catalogs.