WorldCat is a union catalog that itemizes the collections of 72,000 libraries in 170 countries and territories that participate in the Library Center">Online Computer Library Center (OCLC) global cooperative. It is operated by OCLC Online Computer Library Center, Inc. The subscribing member libraries collectively maintain WorldCat's database, the world's largest bibliographic database. OCLC makes WorldCat itself available free to libraries, but the catalog is the foundation for other subscription OCLC services (such as resource sharing and collection management).
OCLC was founded in 1967 under the leadership of Fred Kilgour. That same year, OCLC began to develop the union catalog technology that would later evolve into WorldCat; the first catalog records were added in 1971.
In 2003, OCLC 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 subscribing 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.
As of December 2017, WorldCat contains over 400 million bibliographic records in 491 languages, representing over 2.6 billion physical and digital library assets, and the WorldCat persons dataset (mined from WorldCat) includes over 100 million people.
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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. Consequently:
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.
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.