This is an exciting yet challenging time to be teaching and to be learning about microbiology. The need to provide accurate and current information about the good and bad microbes seems greater than ever. Almost everyday media describes illness arising from contaminated food, the discovery of microbes in an environment once considered impossible to sustain life, the sequencing of another genome, or the dead of another individual from a rare infectious disease. Anyone glancing from the news cannot help but realize the impact that microbes have in our daily lives. This course presents what I believe are the most important facts and concepts about the microbial world and the important role its members play to us every day. An important consideration in developing the course is the diverse interests among our students who take this microbiology course. As always, many students take microbiology course as prerequisite for nursing, allied health, pharmacy, dental, agriculture, and biology programs, or as a step in the pursuit of other fields, including biotechnology, food science, and ecology. A suitable course like this one must provide a solid foundation in basic aspects of microorganisms (covered in the first six (6) chapters), coverage of immune system (chapters 7-9) and infectious disease on organs and systems (chapters 10-16). To address this broad range of aspects and student backgrounds, the course has incorporated numerous learning aids that will facilitate review for some advanced students and will be tremendous support to those who are seeing the material for the first time. I hope you will find that the approach and structure of this course presents a modern and balanced view of microbiology in our world, acknowledging the profound and essential impact that microbes have on our lives today and their role in our lives tomorrow. Enjoy!