  In these lectures we discuss the supersymmetry algebra and its irreducible
representations. We construct the theories of rigid supersymmetry and gave
their superspace formulations. The perturbative quantum properties of the
extended supersymmetric theories are derived, including the superconformal
invariance of a large class of these theories. We also discuss flat directions,
non-holomorphicity and the perturbative chiral effective action for N=2
Yang-Mills theory. The superconformal transformations in four dimensional
superspace are derived and encoded into one superconformal Killing superfield.
It is shown that the anomalous dimensions of chiral operators in a
superconformal quantum field are related to their $R$ weight.
