There have been two earlier Cambridge Tracts that have touched upon the Hardy-Littlewood method, namely those of Landau, 1937, and Estermann, 1952. However there has been no general account of the method published in the United Kingdom despite the not inconsiderable contribution of English scholars in inventing and developing the method and the numerous monographs that have appeared abroad. The purpose of this tract is to give an account of the classical forms of the method together with an outl