Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. This process begins in the esophagus when food is swallowed and continues through the stomach and intestines. The muscles in the walls of these organs contract and relax in a coordinated manner, pushing the food along the digestive system. In addition to aiding digestion, peristalsis also plays a role in the elimination of waste from the body. The rhythmic contractions help to move waste through the colon and out of the rectum. This involuntary process is essential for maintaining a healthy digestive system.