CERN's main focus is particle physics – the study of the fundamental constituents of matter – but the physics programme at the laboratory is much broader, ranging from nuclear to high-energy physics, from studies of antimatter to the possible effects of cosmic rays on clouds.

Since the 1970s, particle physicists have described the fundamental structure of matter using an elegant series of equations called the Standard Model. The model describes how everything that they observe in the universe is made from a few basic blocks called fundamental particles, governed by four forces. Physicists at CERN use the world's most powerful particle accelerators and detectors to test the predictions and limits of the Standard Model. Over the years it has explained many experimental results and precisely predicted a range of phenomena, such that today it is considered a well-tested physics theory.

But the model only describes the 4% of the known universe, and questions remain. Will we see a unification of forces at the high energies of the Large Hadron Collider (LHC)? Why is gravity so weak? Why is there more matter than antimatter in the universe? Is there more exotic physics waiting to be discovered at higher energies? Will we discover evidence for a theory called supersymmetry at the LHC? Or understand the Higgs boson that gives particles mass?