This volume contains contributions of leading scientists which discuss different aspects of the physics that could be explored at the Large Hadron Collider (LHC). The LHC is a machine of discovery and it is widely expected that the much-awaited Higgs boson will be detected by it. Also, other open issues include the production of a quark-gluon plasma, the corrections due to strong interactions, search for dark matter, and new theories of supersymmetry or physics models with extra space-time dimensions.