A Jumping Jack is a physical exercise that involves jumping to a position with legs spread wide and arms raised overhead, then returning to a standing position with feet together and arms at the sides. This exercise is often used in warm-ups and fitness routines to increase heart rate and improve coordination. Jumping Jacks can be performed anywhere and require no special equipment, making them accessible for people of all fitness levels. They are commonly included in workouts for activities like aerobics, military training, and sports conditioning, contributing to overall cardiovascular health and endurance.