Nearly 25 years have passed since eosinophilic esophagitis (EoE) has been recognized as an own, distinct entity. Initial doubts about the existence of this new disease were quickly eliminated by its dramatic increase. Despite intensive research activities with meanwhile more than 300 scientific publications per year, essential questions of pathogenesis and therapy are still unclear today. Nevertheless, it is worthwhile to draw up an interim balance. The purpose of this 2nd edition is to summarize the key parameters of EoE in an understandable way to empower clinicians to care for EoE patients.