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WorldCat is a global library catalog that connects you to collections from over 72,000 libraries worldwide. It contains more than 1.3 billion records covering books, journals, digital media, and archival materials—making it the largest library database accessible to the public.
WorldCat functions as a union catalog—a single searchable database that combines holdings from thousands of independent libraries. The Online Computer Library Center (OCLC) manages this system, which began adding catalog records in 1971.
Before WorldCat, finding a book meant checking each library’s catalog individually. Researchers had no way to know if a title existed elsewhere or which library held a rare edition. WorldCat solved this by creating a shared infrastructure where libraries contribute their cataloging records to one central database.
The system contains records from libraries across 107 countries. These include academic institutions, public libraries, research centers, and specialized collections. Each record shows which libraries own a particular item and whether it’s available.
WorldCat offers free public access through its search interface at worldcat.org. Anyone can search the database without an account. Libraries pay membership fees to contribute records and access additional services like interlibrary loan systems.
Different users rely on WorldCat for specific needs.
Researchers verify bibliographic information—publication dates, publisher details, ISBN numbers, and author names. This matters when confirming sources for citations or tracking down obscure references. A search on WorldCat shows every edition of a work, including translations and variant printings.
Students at institutions with limited collections use WorldCat to locate materials their library doesn’t own. They can request items through interlibrary loan services, which rely on WorldCat data to identify lending libraries and process transfers.
Authors track how their work spreads across library systems. A WorldCat search reveals which institutions acquired their books and how many libraries hold copies. This provides insight into distribution patterns that sales data doesn’t capture.
Librarians depend on WorldCat for collection development and cataloging. Between July 2023 and June 2024, member librarians copy-cataloged 95% of their items from WorldCat records. This saved approximately 59 million hours by eliminating redundant cataloging work.
General readers search WorldCat when hunting for out-of-print titles, rare editions, or materials not available through commercial retailers. The database shows physical locations where these items exist.
WorldCat aggregates cataloging records created by library staff and OCLC’s data quality specialists. When a library acquires an item, staff members either create a new record or attach their library’s information to an existing one.
Each record follows standardized formats—primarily MARC (Machine-Readable Cataloging). This ensures consistency across different systems and allows automated data exchange between libraries.
OCLC staff continuously review and enrich records with corrected information, subject headings, and additional metadata. Partner content providers sometimes add records before materials are published, giving users early access to upcoming releases.
The database updates daily with new acquisitions and changes to existing holdings. However, individual library data may lag if institutions don’t report removals or transfers promptly.
WorldCat covers multiple formats: printed books, journals, manuscripts, maps, films, sound recordings, digital files, and archival materials. It does not index individual journal articles—you need article databases like JSTOR or PubMed for that level of granularity.
Coverage extends from materials dating back to 1000 A.D. through current publications. Historical records vary by region and depend on which libraries have cataloged their older collections.
The basic search interface on worldcat.org accepts keywords, titles, authors, or ISBN numbers. Type your query and select the material type (books, articles, videos, etc.) to filter results.
For better precision, use the advanced search option. This lets you specify:
Search results display by relevance unless you change the sort order. Each result shows the title, author, publication details, format, and number of libraries holding the item.
Click any result to see the full record. This includes a complete bibliographic description, subject classifications, physical description (page count, dimensions), and a list of libraries that own it.
The library list shows institutions by proximity if you’ve set your location. Distance appears next to each library name. Some results include direct links to the library’s catalog or availability status.
When you find an item you need, note which nearby library holds it. You can visit that library directly or submit an interlibrary loan request through your own institution’s system.
To refine searches with many results, use facets on the left sidebar. These let you filter by publication year, language, format, content type, or audience level without starting a new search.
WorldCat’s comprehensiveness depends on member library participation. Not every library worldwide contributes records. Small independent libraries or private collections may not appear.
Real-time availability information varies. The database shows which libraries own an item but doesn’t always reflect current circulation status. A book listed as available might be checked out when you visit the library.
Pre-1900 materials have inconsistent coverage. Libraries with extensive special collections may have cataloged their rare holdings, while others haven’t digitized or shared records for older materials.
Digital access restrictions apply to many items. WorldCat lists e-books and digital materials, but access often requires membership in a specific institution or subscription. You can’t always read materials directly through WorldCat—it points you to the holding library’s system.
Individual journal articles don’t appear as separate records. WorldCat lists journal titles and which libraries subscribe to them, but you need article-specific databases to search within journals.
Foreign language materials outside major academic languages may have limited records. Coverage prioritizes materials in English, Spanish, French, German, and other widely cataloged languages.
WorldCat serves a different purpose than consumer search tools.
Google Books scans book content and offers full-text search with preview pages. WorldCat catalogs books as objects but doesn’t include page contents. Use Google Books to search inside books; use WorldCat to find which libraries own them.
Your local library catalog shows only that institution’s holdings. WorldCat shows thousands of catalogs simultaneously. Search locally first for immediate access, then expand to WorldCat if your library doesn’t have what you need.
Academic databases like JSTOR, PubMed, or EBSCOhost index individual articles within journals. WorldCat lists journal titles but not article-level content. Use article databases for research papers; use WorldCat for books and journal subscriptions.
ISBN databases like ISBNdb or Bowker focus on publishing industry data—availability, prices, and editions in print. WorldCat shows library holdings regardless of commercial availability. Check ISBN databases for purchasing; check WorldCat for borrowing.
Search WorldCat when you need to verify a specific book exists and where to find it. This matters for citing sources correctly or tracking down references that don’t appear in your local catalog.
Use it to locate materials not available in your immediate area. If your public library doesn’t carry academic texts or specialized titles, WorldCat shows which nearby academic libraries do. You can often request visitor access or interlibrary loan.
Check WorldCat when researching publication history. The database shows all editions of a work, including translations, reprints, and format variations. This helps compare versions or identify first editions.
Consult it to confirm bibliographic details. If you have incomplete citation information—missing publication dates, unclear author names, or uncertain publisher details—WorldCat records provide standardized data.
Search WorldCat for rare or out-of-print materials. Even if a book isn’t commercially available, libraries may still hold copies. The database identifies which institutions have the item and whether they participate in interlibrary loan programs.
Use it as a starting point for archival research. Many libraries catalog their special collections and manuscript holdings in WorldCat. This gives you a preliminary inventory before contacting archives directly.
