Bubbles, being a phenomenon of nature, have always been around, but the sport of playing with bubbles didn't really exist before soap. A soap bubble is a thin film of soapy water enclosing air that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. They are often used for children's enjoyment, but they are also used in artistic performances. Assembling several bubbles results in a foam.