The esophagus carries food and liquids from the mouth to the stomach. The stomach slowly pumps the food and liquids into the intestine, which then absorbs needed nutrients. This process is automatic and people are usually not aware of it. People sometimes feel their esophagus when they swallow something too large, try to eat too quickly, or drink very hot or cold liquids.
The muscular layers of the esophagus are normally pinched together at both the upper and lower ends by muscles called sphincters. When a person swallows, the sphincters relax to allow food or drink to pass from the mouth into the stomach. The muscles then close rapidly to prevent the food or drink from leaking out of the stomach back into the esophagus and mouth.
Read more about the esophagus from The National Digestive Diseases Information Clearinghouse (NDDIC). You may wish see our section on Gastroesophageal Reflux. HealthyNJ also has a page on Swallowing Disorders.