WorldCat

WorldCat is a global union catalog of library collections. It aggregates bibliographic records and library holdings from libraries around the world, creating a centralized resource that researchers, students, and the public can use to locate items in participating libraries. The catalog is managed by OCLC, a nonprofit library cooperative that coordinates cataloging, interlibrary loan, and other library services for member institutions.

WorldCat contains millions of records describing books, journals, audiovisual materials, digital resources, and more. Holdings data indicate which libraries own a given item and often provide information about item availability and location. Public access to the catalog is provided through WorldCat.org, a web portal that lets users search across many libraries’ records and find nearby libraries that hold the item or offer related services. Libraries may integrate WorldCat data into their own catalogs through WorldCat Discovery or other interfaces, helping users discover and request materials directly from their local institution.

The system originated in the late 20th century as a cooperative cataloging effort and has since grown into the world’s most widely used bibliographic database. WorldCat serves a range of purposes: helping libraries manage catalogs and interlibrary loan, assisting researchers in locating sources, and supporting collection development and metadata workflows through standardized records. While the database is extensive, it relies on contributions from participating libraries, so coverage can vary by region and item type. Overall, WorldCat functions as a key infrastructure for global library access and resource sharing.