Supersymmetry (Susy) is a symmetry that treats fermionic and bosonic particles as manifestations of the same (super-)field, similarly to the idea that spin-up and spin-down are manifestations of the same spin 1/2 field. This implies that in Susy, concepts as different as matter and forces are just aspects of the same object. The Minimal Supersymmetric Standard Model (MSSM) is the simplest supersymmetric extension of the Standard Model (SM) of strong and electroweak interactions. In the MSSM each particle has a supersymmetric partner, like for example the photinos who are the spin 1/2 partners of the photons.