CERN or European Organization for Nuclear Research, nuclear and particle physics research center straddling the French-Swiss border W of Geneva, Switzerland. Established in 1952 as the provisional European Center for Nuclear Research (the acronym CERN is derived this name in French) and founded formally as the Center's successor in 1954, the European Organization for Nuclear Research is an intergovernmental organization whose activities are sponsored by 20 European countries. CERN is the principal European center for research in particle physics. Its large electron-positron storage ring (the LEP collider) was inaugurated in 1989, upgraded in 1996, and closed in 2000. The Large Hadron Collider (LHC), now under construction, is expected to be operational early in 2007. The World Wide Web, a system of internationally distributed, hypertext-linked materials on the Internet, was originally developed at CERN during the 1980s.

in full Organisation Européenne pour la Recherche Nucléaire formerly Conseil Européen pour la Recherche Nucléaire.

International scientific organization established for collaborative research into subnuclear physics. Headquartered in Geneva, CERN includes extensive facilities at sites on both sides of the Swiss-French border. The results of its experimental and theoretical work are made generally available. It was established in part in order to reclaim European physicists who had emigrated to the U.S. as a result of World War II. In 2000 it had 20 European member nations and several nations with observer status.

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