The main theme of the research presented in this thesis is the search for Supersymmetry, one of the most likely and well-motivated extensions of the standard model of particle physics, in 7 TeV proton-proton collisions delivered by the world's most energetic accelerator — the Large Hadron Collider (LHC). In the Supersymmetry search, the key observable is the "missing transverse energy" (Emiss), which T indicates the signal of the lightest stable supersymmetric particles. These lightest supersymmetric particles are also candidates for the constituents of dark matter ob- served in astronomical observations. The research presented in this thesis consists of two major parts: (1) improving the measurement of the missing transverse energy, and (2) searching for Supersymmetry with an emphasis on the study of fake Emiss T events and on the interpretation of real Emiss events using a framework called the "simplified model".M.S.