The recurrent theme in this text is the delicate balance between microbes and humans, and how recent changes in that balance may bring about changes that have adverse effects, such as emerging infectious diseases and micro-organisms resistant to antibiotics. The text does not, however, focus exclusively on microbes as causal agents, but also portrays them as life-givers responsible for the earth's ability to support higher forms of life. This new text will enable instructors to cover all the essential topics of classic and contemporary microbiology in a standard one-term course and will enthuse your students as they learn about the beauty and diversity, as well as the dangers, of the microbial world in which they live.