|Type of site||Catalog and community|
WorldCat is a union catalog which itemizes the collections of 72,000 libraries in 170 countries and territories which participate in the Online Computer Library Center (OCLC) global cooperative. It is built and maintained collectively by the participating libraries.
The catalog was created in 1971 and, as of January 2013[update], it contains more than 289 million different records pointing to over 1.93 billion physical and digital assets in more than 470 languages. It is the world's largest bibliographic database. OCLC makes WorldCat itself available free to libraries, but the catalog is the foundation for other fee-based OCLC services (such as resource sharing and collection management). WorldCat was founded by Fred Kilgour in 1967.
In 2003, Charles A Martinez began the "Open WorldCat" pilot program, making abbreviated records from a subset of WorldCat available to partner Web sites and booksellers, to increase the accessibility of its member libraries' collections. In 2006, it became possible to search WorldCat directly at its website. In 2007, WorldCat Identities began providing pages for 20 million "identities", predominantly authors and persons who are the subjects of published titles.
WorldCat operates on a batch processing model rather than a real-time model. That is, WorldCat records are synchronized at intermittent intervals with the underlying library catalogs instead of real-time or every day. WorldCat shows that a particular item is owned by a particular library, but does not provide that library's call number. It also does not indicate if the item is currently borrowed, lost, undergoing restoration or repair, or moved to storage not directly accessible to patrons (thereby forcing them to submit a retrieval request and wait). WorldCat also does not show if a library owns multiple copies of a particular title.
As an alternative, WorldCat allows participating institutions to add direct links from WorldCat to their own catalog entries for a particular item, which enables the user to determine its real-time status. However, this still requires users to open multiple Web pages, each pointing to a different OPAC with its own distinctive user interface design (which places item status in a different portion of the Web browser display), until they can locate a catalog entry that shows the item is currently available at a particular library.
- "WorldCat facts and statistics". Online Computer Library Center. 2011. Retrieved November 6, 2011.
- Margalit Fox (August 2, 2006). "Frederick G. Kilgour, Innovative Librarian, Dies at 92". The New York Times. Retrieved 2009-12-22. "Frederick G. Kilgour, a distinguished librarian who nearly 40 years ago transformed a consortium of Ohio libraries into what is now the largest library cooperative in the world, making the catalogs of thousands of libraries around the globe instantly accessible to far-flung patrons, died on Monday in Chapel Hill, N.C. He was 92."
Further reading 
- Grossman, Wendy M. (21 January 2009). "Why you can't find a library book in your search engine". The Guardian.