Inside WorldCat
WorldCat consists of three components: a bibliographic catalog, a knowledge base, and a registry for library information.
The WorldCat bibliographic catalog includes everything that’s available to users in the library. Beyond books and print journals, the catalog of physical materials includes DVDs, historic photos, video games, musical scores, newspapers, webpages and many other standard items. It also includes unique items, such as 2,700-year-old jewelry and memorabilia from historic car races.
In 1971, librarians in Alden Library at Ohio University added the first bibliographic records to what was then known as the OCLC Online Union Catalog. Within eight years, the catalog already included more than five million records. Now known as WorldCat, the catalog today includes millions of records and billions of holdings.
As the WorldCat bibliographic catalog continues to grow in quantity, efforts to improve the quality also increase. Professional catalogers all over the world consistently improve WorldCat records to make them as complete and useful as possible. This cooperative resource simplifies cataloging, maintenance, interlibrary loan and discovery tasks for libraries worldwide.
How WorldCat evolves
WorldCat has continued to keep up with the way modern library users prefer to consume media. From print books to streaming video and beyond, you can find it in WorldCat. Here are a just a few of the many formats that have been added to WorldCat over the years.
| WorldCat launches with: | |
|---|---|
|
Books Theses Atlases Articles Musical scores |
|
| 1971 |
Serials Photos/Images Films Audio cassettes Sound recordings |
| 1975 |
Newspapers Computer files |
| 1980 |
Floppy discs |
| 1986 |
Audio CDs |
| 1987 |
CD-ROMs |
| 1996 |
DVD-ROMs |
| 2000 |
Streaming video |
| 2008 |
Blu-ray discs |
Italicized years are approximate
![Scott Seaman [photo]](/content/dam/oclc/worldcat/update/photo_scott_seaman.png){kind=small}
“The world’s knowledge…”
Vital statistics
WorldCat growth
Number of bibliographic records
586,648,074 (as of December 2024)
Number of holdings
3,521,359,124 (as of December 2024)
+3.14%
Bibliographic records
+4.38%
Holdings
+5.59%
Local holdings
+5.77%
Local bibliographic data
(July 2023–June 2024)
WorldCat gets more than one new record
every second
Members fill an ILL request
every second
Language composition of WorldCat items
Non-English
61%
English
39%
(as of January 2025)
Number of languages
488 (as of January 2025)
More language statistics
Scripts represented in WorldCat
The WorldCat knowledge base connects library users to the electronic content provided by their library. It combines data about a library’s e-resources with linking features that make the collections easier to find, share, manage and use. Like data in the WorldCat bibliographic catalog, knowledge base data are not tied to a particular application, so libraries can streamline electronic content workflows across multiple systems.
The WorldCat knowledge base’s cooperatively maintained collections continue to grow with content from libraries and publishers from around the world. Because OCLC is a nonprofit, vendor-neutral global library organization, the WorldCat knowledge base is the only source that includes records from both EBSCO and ProQuest, Gale and Springer, and Wiley and Elsevier, among many other content suppliers.
The knowledge base also includes free and open-access materials that users can find and get alongside their library’s materials. As of September 2024, the knowledge base provides access to more than 85,235,697 records and 29,601 content collections from 679 providers. Download an Excel spreadsheet that lists all knowledge base collections to see what’s available today.
Sharing holdings to improve discovery
![Maurine McCourry [photo]](/content/dam/oclc/worldcat/update/photo_maurine_mccourry.jpg){kind=small}
“Drastically improved discovery…”
The WorldCat registry allows libraries to maintain information about their services and contacts to help information seekers find the library online. When librarians maintain their institution’s location, hours, relationships, services and contact information, the WorldCat registry populates that information on WorldCat.org and elsewhere through links on popular websites. Library staff can also share profiles with vendors and consortium members to ensure they always have the most accurate contact information.
Visit the WorldCat registry
Find in a Library links
Services across the internet help people find great books to read. The WorldCat data embedded into those websites through “Find in a Library” links help direct readers to libraries near them that hold the book they want. The WorldCat registry provides the location and other information needed to connect libraries with readers.
