Regurgitation refers to the backward flow of gastric contents into the oesophagus or mouth, often due to dysfunction of the lower oesophageal sphincter. It is clinically significant as it can lead to complications such as gastro-oesophageal reflux disease (GERD), which may result in oesophagitis, Barrett's oesophagus, or aspiration pneumonia. Understanding regurgitation is crucial for diagnosing and managing conditions affecting the gastrointestinal tract.