Infectious disease is something that effects and surely interest everyone, but for a clear picture of what actually happens during an infection, it is usually necessary to consult one or more large textbooks, since the subject falls across the conventional disciplines of microbiology, immunology, pathology, pharmacology, epidemiology, and medicine. This book summarizes the essentials in a way that can be understood by any student or potential student of science or medicine and presupposes no previous knowledge of either microbiology or immunology. The style has been kept as close as possible to actual lectures and tutorials, including an element of self-testing and a guide to the books that can be, if desired, used for delving deeper into the subject.