Abstract : Supersymmetry is an attractive extension of the standard model of particle physics. It associates to every bosonic degree of freedom a fermionic one and vice versa. Supersymmetry unifies the coupling constants of the electromagnetic, weak and strong forces at a high scale and provides a candidate for the elusive dark matter. Supersymmetry could be discovered at the LHC, the proton--proton collider at CERN which has started operations in 2008. The LHC is foreseen to have a center--of--mass energy of 14~TeV, opening up a new mass range to be explored to search for supersymmetric particles with the ATLAS and CMS experiments. The development and production of electronics for these detectors has been a challenge, e.g. for the readout board for the electromagnetic calorimeter. Reconstructing the physics events with the best precision, in particular the reconstruction and identification of electrons and photons in the large QCD background has been prepared in extensive test beam studies and Monte Carlo simulations. If the Higgs boson and supersymmetry are discovered, the properties of the (s)particles such as the masses, branching ratios must be measured precisely, either at the LHC or at a future e+e- linear collider. The SFitter project aims to determine the underlying theoretical model parameters from the correlated experimental measurements including theoretical errors. The methods are applied to the extraction of the fundamental parameters of supersymmetry as well the measurement of the Higgs boson couplings at the LHC. The extrapolation of the supersymmetric parameters from the weak scale to the Grand Unification Scale could provide the basis towards the inclusion of gravity.