Online Computer Library Center. A non-profit cooperative organization of libraries that serves to share data and make cataloging easier. OCLC includes over 43,000 libraries in 86 countries, and provides quick information to booksellers and collectors about which libraries have a copy of a particular title. Access to OCLC is by fee-based subscription service, most commonly available at libraries, but also offers public access at www.worldcat.org. Searches within Worldcat provide an indication of the scarcity of an item.