Biology is a branch of science which deals with the study of living organism. It also referred as natural Science. This book focus on basic understands about classification of living organisms, genetics, biomolecules, energy metabolism and microbiology. The classification of living organisms based on morphological, biochemical and ecological aspects. In genetics, the concepts of Mendel's laws of inheritance to predict single gene disorder in human. The biomolecules chapter is dedicated on dietary biomolecules for healthy life. Metabolism chapter is focal point on energy metabolism and energy transfer in biological systems. Last chapter is about the basic introduction to microbiology in context with classification and identification of microorganisms. This chapter also gives outline about the structure, types and pathogenesis of virus. This book is designed for engineering students to overcome their possible fear about biology and address the biological aspects with confidence. This book also provides the fundamentals of biology in an easy manner that increases interest among the engineering students.