Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. This involuntary process occurs in the esophagus, stomach, and intestines, helping to push contents along the digestive system. It involves the coordinated contraction and relaxation of circular and longitudinal muscles, ensuring efficient digestion and absorption of nutrients. Peristalsis is essential for maintaining the flow of food and waste through the gastrointestinal system.