Acid Reflux Disease, also known as Gastroesophageal Reflux Disease (GERD), occurs when stomach acid frequently flows back into the esophagus. This backflow, or reflux, can cause symptoms like heartburn, regurgitation, and difficulty swallowing. It happens when the lower esophageal sphincter, a muscle that normally keeps stomach contents from rising, weakens or relaxes improperly. Chronic acid reflux can lead to more serious health issues, such as esophagitis or Barrett's esophagus, which can increase the risk of esophageal cancer. Lifestyle changes, medications, and in some cases, surgery can help manage the symptoms and prevent complications.