This document provides an overview of microbiology and the classification of microorganisms. It discusses the early history of microbiology including the development of the microscope and experiments by scientists like Redi, Pasteur, and Koch. Microbes are classified into six categories: fungi, protozoa, algae, bacteria, archaea, and small animals. Bacteria and archaea are further described. The document also covers disease transmission, prevention, and treatment as well as the fields of biochemistry, genetics, immunology, and emerging diseases.