This book contains a general historical survey covering events leading to the establishment of the semiconductor industry and its subsequent development up to the middle of the 1980s. Although a description of the technical developments of semiconductor devices during this period forms an essential part of the work, treatment in this respect has been largely of a descriptive nature, with the minimum of technical detail. The origins of semiconductor development are largely bound up with that of the thermionic valve industry, and this aspect has been taken into account by including a brief description in chapter 2 entitled "the development of the thermionic valve". The growth of the semiconductor industry has been considered within our basic geographical divisons, namely the United States, Western Europe, Eastern Europe and Japan. The decision to adopt this approach was more than a matter of convenience, since the national semiconductor industries included within these areas appear to share certain common problems, and have evolved in a similar manner. Nevertheless, in view of their importance, the international character of the industry and the manner of diffusion of technical information and manufacturing processes have also received attention.