Swing In The Underground, San Francisco, United States

A swing is a hanging seat, usually found in a playground for children, a circus for acrobats, or on a porch for relaxing. The seat of a swing can be attached to a chain or a rope. Once a swing is in motion it continues to oscillate like a pendulum until external interference or drag brings it to a halt. Swing sets are very popular amongst children.
On playgrounds, several swings are often suspended from the same metal or wooden frame, known as a swing set, allowing more than one child to play at a time. Such swings come in a variety of sizes and shapes. For infants and toddlers, swings with leg holes support the child in an upright position while a parent or sibling pushes the child to get a swinging motion. Some swing sets include play items other than swings - such as a rope ladder or sliding pole.
For older children, swings are sometimes made of a flexible canvas seat, of rubberized ventilated tire tread, of plastic, or of wood. A common backyard sight is of a wooden plank suspended on both sides by ropes from a tree branch. Older children can go much higher, sometimes over 15 feet (5 m) above the ground. In the United States, some adults go to the extreme and compete in the NSA, "National Swing Association", where competitors reach heights over 20 feet, while leaping at the peak of their swing.