The generalized unitarity method reconstructs loop-level scattering amplitudes from tree-level scattering amplitudes. We review some of the steps of this method which are necessary for applications in any quantum field theory, discuss several points of view and emphasize some of the aspects that can be easily automated.
We mainly use N=4 super-Yang-Mills theory to illustrate the discussion and comment on the necessary changes for applications to super-Yang-Mills theories with reduced supersymmetry.