WorldCat is a union catalog that itemizes the collections of tens of thousands of institutions (mostly libraries), in many countries, that are current or past members of the OCLC global cooperative. It is operated by OCLC, Inc. Many of the OCLC member libraries collectively maintain WorldCat's database, the world's largest bibliographic database. The database includes other information sources in addition to member library collections. 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). WorldCat is used by librarians for cataloging and research and by the general public.
As of December 2021[update], WorldCat contained over 540 million bibliographic records in 483 languages, representing over 3 billion physical and digital library assets, and the WorldCat persons dataset (mined from WorldCat) included over 100 million people.
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 October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was later phased out, although WorldCat later incorporated user-generated content in other ways.
In 2006, it became possible for anyone to search WorldCat directly at its open website WorldCat.org, not only through the subscription FirstSearch interface where it had been available on the web to subscribing libraries for more than a decade before. Options for more sophisticated searches of WorldCat have remained available through the FirstSearch interface.
In 2017, OCLC's WorldCat Search
In May 2022, OCLC announced WorldCat Entities, a new infrastructure for library linked data. Maintenance of WorldCat Identities was suspended and the service will be discontinued as it is being replaced by WorldCat Entities.
In August 2022, OCLC launched a "redesigned and reimagined" WorldCat.org website with the stated goal "to offer greater accessibility to the collections".
Local catalogs of many OCLC member libraries are intermittently synchronized with the WorldCat database. WorldCat allows participating institutions to add direct links from WorldCat to their own local catalog entries for particular items, which enables the user to click through to the local catalog to quickly determine an item's real-time status (for example, whether or not it is checked out).
Library contributions to WorldCat are made via the Connexion computer program,
- Faceted Application of Subject Terminology (FAST)
- List of academic databases and search engines
- Open Library
- "Search for library items". WorldCat. OCLC. Archived from the original on September 22, 2007. Retrieved March 29, 2017.
- 1998 is the date of registry of the WorldCat.org domain; see: "WorldCat.org WHOIS, DNS, & Domain Info – DomainTools". WHOIS. Archived from the original on June 20, 2019. Retrieved January 21, 2017. However, the union catalog that became WorldCat was started three decades earlier, and it was already available on the web to subscriber libraries at OCLC.org several years before WorldCat.org was a registered domain name; see: "OCLC.org WHOIS, DNS, & Domain Info – DomainTools". WHOIS. Archived from the original on June 26, 2019. Retrieved June 26, 2019.
- "Inside WorldCat". www.oclc.org. OCLC. Archived from the original on January 30, 2017. Retrieved June 19, 2021.
- "Content available through WorldCat Discovery" (XLS). www.oclc.org. OCLC. Archived from the original on September 22, 2020. Retrieved September 22, 2020.
- "Data strategy [WorldCat]". oclc.org. Archived from the original on March 27, 2019. Retrieved February 11, 2018.
- Margalit Fox (August 2, 2006). "Frederick G. Kilgour, Innovative Librarian, Dies at 92". The New York Times. Archived from the original on April 25, 2009. Retrieved December 22, 2009.
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.
- "A brief history of WorldCat". oclc.org. February 10, 2015. Archived from the original on March 18, 2013. Retrieved February 13, 2014.
- Quint, Barbara (October 27, 2003). "OCLC project opens WorldCat records to Google". infotoday.com. Information Today. Archived from the original on April 11, 2015. Retrieved June 26, 2019.
- "WikiD". OCLC. Archived from the original on September 12, 2012. Retrieved March 5, 2015.
- Hane, Paula J. (July 17, 2006). "OCLC to open WorldCat searching to the world". infotoday.com. Information Today. Archived from the original on May 10, 2020. Retrieved June 26, 2019.
- "OCLC and Wikipedia Library link citations to millions of library materials, expanding access to quality sources". oclc.org. OCLC. May 11, 2017. Archived from the original on December 9, 2017. Retrieved April 25, 2020.
- Orlowitz, Jake (May 11, 2017). "You can now add automatically generated citations to millions of books on Wikipedia". blog.wikimedia.org. Wikimedia Foundation. Archived from the original on May 23, 2020. Retrieved April 25, 2020.
- Michalko, Jim (October 12, 2017). "Syncing Catalogs with thousands of Libraries in 120 Countries through OCLC". blog.archive.org. Internet Archive. Retrieved July 18, 2020.
- "Find WorldCat Entities to improve resource discoverability through connections". www.oclc.org. Archived from the original on May 24, 2022. Retrieved March 25, 2023.
- "WorldCat Identities". OCLC. March 9, 2023. Archived from the original on March 25, 2023. Retrieved March 15, 2023.
The research prototype application is no longer supported or maintained ... We have taken the findings of the research effort and used them to start to build the WorldCat Entities data. These new Entities and their persistent URIs will serve as the foundation for future linked data services similar to those explored in the Identities Research work.
- "Frequently Asked Questions". WorldCat. Archived from the original on August 29, 2022. Retrieved August 29, 2022.
- "About data sync collections – OCLC Support". www.oclc.org. OCLC. April 14, 2017. Archived from the original on June 18, 2021. Retrieved June 18, 2021.
- "What is WorldCat?". worldcat.org. Archived from the original on November 14, 2019. Retrieved February 13, 2015.
- Schonfeld, Roger C. (December 5, 2019). "What are the larger implications of Ex Libris buying Innovative?". sr.ithaka.org. Archived from the original on June 12, 2020. Retrieved April 25, 2020.
OCLC's WorldShare cloud system has yet to achieve critical mass, amounting to 10% of the academic market (but only 4% of ARL), and OCLC's entire public library business represents just 10% of the public library market.For another source of statistics on library system market share, see: "Library Technology Guides: Marketshare Report". librarytechnology.org. Archived from the original on July 28, 2021. Retrieved June 18, 2021.
- "Connexion – Features". www.oclc.org. OCLC. Archived from the original on June 24, 2021. Retrieved June 18, 2021.
- Dean, Becky (March 3, 2005). "OCLC Authorities migration timeline". [email protected] (Mailing list). Retrieved June 26, 2019.
- "WorldShare Record Manager: Record-at-a-time cataloging service". www.oclc.org. OCLC. April 2, 2021. Archived from the original on June 24, 2021. Retrieved June 18, 2021.
- "WorldCat Metadata API | OCLC Developer Network". www.oclc.org. OCLC. Archived from the original on June 5, 2021. Retrieved June 18, 2021.
- "OCLC cataloging application comparison". www.oclc.org. OCLC. Archived from the original on June 18, 2021. Retrieved June 18, 2021.
- Blackman, Cathy; Moore, Erica Rae; Seikel, Michele; Smith, Mandi (July 2014). "WorldCat and SkyRiver: a comparison of record quantity and fullness". Library Resources & Technical Services. 58 (3): 178–186.
- Breeding, Marshall (May 2015). "Library services platforms: a maturing genre of products". Library Technology Reports. 51 (4): 1–38. doi:10.5860/ltr.51n4.
- Matthews, Joseph R. (July 2016). "An environmental scan of OCLC alternatives: a management perspective". Public Library Quarterly. 35 (3): 175–187.
- McKenzie, Elizabeth (January 2012). OCLC changes its rules for use of records in WorldCat: library community pushback through blogs and cultures of resistance (Technical report). Boston: Suffolk University Law School. Research paper 12-06.
- What the OCLC online union catalog means to me: a collection of essays. Dublin, Ohio: OCLC. 1997. OCLC 37492023.
- Wilson, Kristen (August 2016). "The knowledge base at the center of the universe". Library Technology Reports. 52 (6): 1–35. doi:10.5860/ltr.52n6.
- "WorldCat data licensing" (PDF). OCLC. Archived (PDF) from the original on December 31, 2018. Retrieved December 31, 2018. See also: "Data licenses & attribution". oclc.org. January 14, 2017. Archived from the original on December 31, 2018. Retrieved December 31, 2018. Information about licensing of WorldCat records and some other OCLC data.