The aim of this book is to present the subject of Biotechnology to the Graduate and Post graduate students of Biotechnology of various universities of India. The authors have been extra cautious in presenting the matter in easy and lucid language. The diagrams are especially designed for clarity and simplicity. Thus, in this book many topics which are not easily available have been incorporated for the convenience of the students. So, the non-availability of literature, we started a sincere effort to search, collate, and edit the various topics. This was a challenging job. The completion of the book has not at all easy task. It has been completed with the co-operation of so many hands.