Our own experience shows that there is no simple, yet of good scientific and clinical quality guide for practitioners and patients on gastrointestinal diseases. In the proposed book we will cover a vast area in the field, from GI tract physiology to disease diagnosis and treatment, in a comprehensive and approachable manner. The guide will not replace online resources (often used by patients) or specialized editions addressing experienced medical doctors, but rather fill the gap between those two. Our aim is to design this book so that it appeals to a wider audience; yet - if needed - encourages to explore the field further.