Gastroesophageal reflux disease (GERD) occurs when the lower esophageal sphincter fails to close properly, leading to acid reflux and symptoms like heartburn, regurgitation, and dyspepsia. Treatment includes lifestyle changes, medications such as antacids and proton pump inhibitors, and possible surgical options like fundoplication or endoscopic procedures. Early diagnosis and tailored treatment plans are essential to manage symptoms and prevent complications.