Acid reflux, also known as gastroesophageal reflux disease (GERD), occurs when stomach acid flows back up into the esophagus, causing a burning sensation in the chest known as heartburn. This condition is often characterized by symptoms such as regurgitation, sour taste in the mouth, and difficulty swallowing. Acid reflux occurs when the lower esophageal sphincter (LES), a muscle at the bottom of the esophagus, weakens or relaxes inappropriately, allowing stomach acid to travel upward. Factors contributing to acid reflux include obesity, certain foods and drinks, smoking, and pregnancy. Chronic acid reflux can lead to complications such as esophagitis, ulcers, and narrowing of the esophagus. Treatment options include lifestyle changes, such as dietary modifications and weight loss, as well as medications to reduce stomach acid production and improve LES function. In severe cases, surgery may be necessary to strengthen the LES or correct anatomical abnormalities.