Every since the days of Rene Descartes, the French philosopher, mathematician and biologist of seventeenth century, all human knowledge especially natural sciences were directed to develop technologies which add to the creature comforts of human lives as also value to human life. the whole approach to understanding natural phenomenon became anthropocentric physics and chemistry gave rise to engineering, technologies and industries which all worked for human comfort and welfare The major utility of the biological worlds is as a source of food Biothechnology, the twentieth century off shoot of modern biology changed our daily life as its products brought qualitative improvement in health and food production. the basic principles underlying biotechnological processes and some application are highlighted and discussed in this unit.