This publication presents an overview of the field of infectious diseases in its entirety, reflecting particularly the modern content of the discipline. It turns away from the description of classical community infections, instead focusing on new diseases and a new view of old infections. The book opens with an explanation of general terms in epidemiology, pathogenesis and the course of infections. The general part presents the principles of diagnosing, treatment and prevention. The core of the textbook includes a systematic exposition of individual infectious diseases arranged according to organ systems. The chapters are treated in a uniform manner, first presenting the common symptoms, followed by a description of nosological units and, finally, offering a key to the identification and differential diagnostics of the described diseases. The third part completes the information on infectious diseases from the perspective of the method of transmission and the circumstances surrounding the beginning of the diseases. It also pays attention to imported infections, to individuals with immunity disorders, specific groups of patients, infections arising in connection with providing healthcare and to highly dangerous infections. Each topic is described from multiple perspectives which helps the readers not to omit key facts. The textbook respects modern trends in the field and its current needs. As it presents issues in broader context, the book allows for the acquired information to be used in other medical fields and in clinical practice.