Swimming is the activity of holding and moving forward, using the arms and legs, on or under the water. It can be done as a recreational activity or as a competitive sport. Because humans do not swim instinctively, swimming is a skill that must be learned.
The main obstacle to learning to swim is the fear of water or nervousness, which produces muscular tension. Much progress has been made in the development of methods to reduce this psychological barrier. Children are often taught to children from an early age.
The movements that are made in the water to advance are swimming styles and it is the evolution of competitive swimming as a sport. Swimming can be practiced in any type of water enclosure large enough to allow free movement.