ILC: Physics scenarios

Experiments in the energy range form the scale of electroweak symmetry breaking to the TeV scale are expected to be crucial for unraveling the microscopic structure of matter and forces. The high precision which should be achieved in experiments at lepton colliders, is a necessary ingredient for providing a comprehensive picture of the mechanism breaking the electroweak symmetries and generating mass, the unification of forces, involving most likely supersymmetry, and the structure of space-time at small distances. In addition, clarifying the nature of the particles which build up cold dark matter in the universe, needs a lepton collider to match the high experimental precision which will be reached in cosmology experiments. (orig.)