Final answer:
GERD is a chronic digestive disorder that affects the lower esophageal sphincter. It commonly affects adults and is caused by various factors.
Step-by-step explanation:
Gastroesophageal reflux disease (GERD) is a chronic digestive disorder that affects the lower esophageal sphincter (LES), the muscle that connects the esophagus and stomach. It happens when the LES weakens or relaxes, allowing stomach acid to flow back up into the esophagus, causing heartburn and other symptoms.
GERD commonly affects people of all ages, but it is more prevalent in adults. Factors that can contribute to GERD include obesity, pregnancy, smoking, certain medications, and certain foods and drinks.