This document discusses the history and scope of microbiology. It begins by defining microbiology as the study of microorganisms, which are tiny creatures that can only be seen under a microscope. It then describes the branches of microbiology, including pure microbiology which focuses on taxonomy and integration of microbes, and applied microbiology which examines medical, veterinary, industrial, and other applications. The document continues by outlining the major groups of microorganisms and how they are named and classified. It concludes with an overview of the key discoveries and scientists that helped establish microbiology as a field, including the germ theory of disease and development of antibiotics.