The book aims to provide a reader with comprehensive information on the basic biological concepts from the beginning of evolution to advanced topics. The chapters are presented in a systematic way where the readers are first introduced to the need for biology in present era. Then the following chapters discuss events that led to the origin of life, cell and their contents, biomolecules of cells, metabolic activities in cells, hereditary materials of cells, the microbial world around us and our body’s defense system for protecting from disease-causing microbes. Each chapter has been presented more immaculately with a simpler illustration that makes the reader understand the concepts. A Set of practice questions has been provided at the end of the chapter.