  In this talk we review recent developments which enable us to use techniques
of integrable two-dimensional quantum field theories to solve exactly four
dimensional N=4 gauge theory through the use of the AdS/CFT correspondence. By
`solve' we mean here to find all anomalous dimensions of all operators of the
theory for any value of the gauge coupling. We illustrate the methods with the
case of the Konishi operator, the simplest operator not protected by
supersymmetry, whose perturbative anomalous dimension can be computed from the
string side of the AdS/CFT correspondence and is in exact agreement with a
direct gauge theory perturbative computation.
