What exactly is a union catalog? The idea behind a union catalog is to earn time by avoiding the cataloging of the same document by many catalogers worldwide. When catalogers of a member library (paid subscription) process a new document, they first search the union catalog. If the record is available, they import it into their own catalog and add the local data. If the record is not available, they create it in their own catalog and export it into the union catalog, for the new record to be instantly available to all catalogers of member libraries. Depending on their status and experience, member libraries can either import records only, or both import and export records. OCLC (Online Computer Library Center) was created in 1971 as a non- profit organization dedicated to furthering access to the world's information while reducing information costs. The OCLC Online Union Catalog, later renamed WorldCat, was first the union catalog of the university libraries in the State of Ohio, before becoming a national library cooperative and then an organization spreading worldwide, with WorldCat becoming one of the two largest union catalogs in the world (the other one being RLIN). In early 1998, WorldCat had 38 million records in 400 languages, and 27,000 member libraries in 65 countries, with 2 million records added annually. WorldCat only accepted one bibliographic record per document, unlike RLIN, launched by RLG in 1980, that accepted several records per document, with 88 million records in early 1998. RLG members were mainly research and specialized libraries. RLIN was later renamed the RLG Union Catalog. Its free web version RedLightGreen was launched in fall 2003 as a beta version, and in spring 2004 as a full version. In the meantime, WorldCat had 61 million bibliographic records in 400 languages in 2005, from 9,000 member libraries in 112 countries. In 2006, 73 million bibliographic records were linking to one billion documents available in these libraries. In August 2006, WorldCat began migrating to the web with the beta version of its new website worldcat.org. Member libraries have provided free access to their catalogs, and free or paid access to their electronic resources: books, audiobooks, abstracts and full-text articles, photos, music CDs and videos. RedLightGreen closed its site in November 2006, and RLG merged with OCLC. In April 2010, 1,5 billion documents could be located and/or accessed using WorldCat. 2007 > THE ENCYCLOPEDIA OF LIFE, A GLOBAL EFFORT