Calisthenics are a form of exercise consisting of a variety of simple bodyweight movements, generally without using equipment. They are used to increase body strength, endurance, and flexibility with movements such as bending, jumping, swinging, twisting or kicking. Calisthenics are usually performed in high volume (lots of sets and reps) because the only resistance is bodyweight. When it is done vigorously enough, it can build stamina, agility, and coordination.
Sports teams, military units, and other groups, use calisthenics with a leader directing the group. This is used as physical training that also builds unity and discipline in the group.
Some elementary and junior high schools implement calisthenics into physical education programs in order to teach big groups of kids the basics of exercising.