Theory of the Muon Anomalous Magnetic Moment The theory of the muon anomalous magnetic is particle physics in a nutshell and as such is interesting exciting and difficult. The current precision of the experimental value for this quantity improved significantly in the past several years due to experiment E821 at Brookhaven National Laboratory is so high that a large number of subtle effects not relevant previously become important for the interpretation of the experimental result. The theory of the muon anomalous magnetic moment is at the cutting edge of current research in particle physics and includes multiloop calculati