CERN is the European Organization for Particle Physics Research, the world's largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. The convention establishing it was signed on September 29, 1954. From the original 12 signatories of the CERN convention, membership has grown to the present 20 Member States.
The acronym originally stood, in French, for Conseil Européen pour la Recherche Nucléaire (European Council for Nuclear Research), which was a provisional council for setting up the laboratory, established by 11 European governments in 1952. The acronym was retained  for the new laboratory after the provisional council was dissolved, and informally changed to Centre Européen pour la Recherche Nucléaire (European Centre for Nuclear Research).
CERN currently employs just under 3000 people full-time. Some 6500 scientists and engineers (representing 500 universities and 80 nationalities), about half of the world's particle physics community, work on experiments conducted at CERN.
The CERN accelerator complex has six main accelerators:
It also has very impressive computer and wide-area networking facilities which are primarily used for experimental data analysis.
Most of the activities at CERN are currently directed towards building a new collider, the Large Hadron Collider (LHC) and the experiments for it, due to start operation in 2007. This will use the 27 km circumference circular tunnel previously occupied by LEP which was closed down in November 2000, and the PS/SPS complex to pre-accelerate protons which will be injected into it.
Decommissioned accelerators include:
There is also the Antiproton Decelerator (AD), which reduces the speed of antiprotons (which are created travelling at nearly the speed of light) for research into antimatter.
The World Wide Web began as a CERN project.
The original CERN signatories were:
 According to Lew Kowarski, a former director of CERN, when the name was changed, and the acronym could have become the awkward OERN, Heisenberg said "But the acronym can still be CERN even if the name is ...