The branch of medicine that studies the digestive system and its disorders is referred to as gastroenterology. Diseases related to the gastrointestinal tract, namely the stomach, oesophagus, small intestine, large intestine and rectum, and the organs responsible for digestion, which includes the liver, gallbladder and pancreas are known as gastrointestinal diseases. Some oral diseases associated with the gastrointestinal tract include gastroesophageal reflux disease, Gardner's syndrome, Peutz–Jeghers syndrome, atrophic glossitis, angular cheilitis and sideropenic dysphagia. Some other diseases associated with the gastrointestinal tract include oesophageal diseases, such as Barrett's oesophagus, gastric diseases such as atrophic gastritis, intestinal diseases such as enterocolitis and liver diseases such as fatty liver. This book aims to shed light on some of the unexplored aspects of gastrointestinal medicine. It will also provide interesting topics for research which interested readers can take up. This book includes contributions of experts and doctors which will provide innovative insights to readers.