  In this chapter of "Review of AdS/CFT Integrability" we introduce N=4 Super
Yang-Mills. We discuss the global superalagebra PSU(2,2|4) and its action on
gauge invariant operators. We then discuss the computation of the correlators
of certain gauge invariant operators, the so-called single trace operators in
the large N limit. We show that interactions in the gauge theory lead to mixing
of the operators. We compute this mixing at the one-loop level and show that
the problem maps to a one-dimensional spin chain with nearest neighbor
interactions. For operators in the SU(2) sector we show that the spin chain is
the ferromagnetic Heisenberg spin chain whose eigenvalues are determined by the
Bethe equations.
