  The discovery of a light Higgs boson at the LHC opens a broad program of
studies and measurements to understand the role of this particle in connection
with New Physics and Cosmology. Supersymmetry is the best motivated and most
thoroughly formulated and investigated model of New Physics which predicts a
light Higgs boson and can explain dark matter. This paper discusses how the
study of the Higgs boson connects with the search for supersymmetry and for
dark matter at the LHC and at a future $e^+e^-$ collider and with dedicated
underground dark matter experiments.
