The branch of medicine which is concerned with the disorders of the digestive system is known as gastroenterology. Diseases of stomach, intestine, colon, rectum, esophagus, gall bladder and liver are key areas of study under this discipline. It also involves a detailed understanding of the physiology of gastrointestinal organs. This comprises the study of removal of waste, digestion and absorption of nutrients, and movement of material through the digestive system. Gastroenterology also focuses on the treatment of various conditions such as colon polyps, hepatitis, gastroesophageal reflux, colitis and pancreatitis. The treatment can also include procedures such as colonoscopy, liver biopsy, endoscopic ultrasound and endoscopic retrograde cholangiopancreatography. Such selected concepts that redefine gastroenterology have been presented in this book. From theories to research to practical applications, case studies related to all contemporary topics of relevance to this field have been included herein. This book is a vital tool for all researching or studying gastroenterology as it gives incredible insights into emerging trends and concepts.