A soap bubble is a very thin film of soap water that forms a sphere with an iridescent surface. A bubble can exist because the surface layer of a liquid (usually water) has a certain surface tension, which causes the layer to behave somewhat like an elastic sheet. However, a bubble made with a pure liquid alone is not stable and a dissolved surfactant such as soap is needed to stabilize a bubble.
Soap bubbles usually last for only a few moments and then burst either on their own or on contact with another object. They are often used as a children’s plaything, but their usage in artistic performances shows that they can be fascinating for adults too.