The present text has been designed to outline the basic and fundamental aspect of biotechnology to be understood in its right perspective. It envisages to put forward a clear understanding of “what is biotechnology” and its widening horizons. The text concentrates on the essential aspects of Biotechnology and thus provide the student with a broadly based overview of subject. This edition includes new species, phylogenetic relationships and a greater emphasis on Environmental and ecological matters, whilst retaining the traditional strengths of the provide edition. Thus the scope of each chapter has been broadened enough to provide information on historical landmarks as well as new facts from current issues of major journals. Chapters have received special attention to make the student aware of future possibilities in Biotechnology.