Silly Putty is the Crayola owned trademark name for a class of silicone polymers. It is marketed today as a toy for children, but was originally created by accident during research into potential rubber substitutes for use by the United States in World War II.
It was after its success as a toy that other uses were found. The material's unique properties have found niche use in medical and scientific applications. It is used in large quantity by physical therapists for rehabilitative therapy of hand injuries. A number of other brands have emerged which alter the material's properties offering different levels of resistance for this market. Power Putty and TheraPutty are examples. Though primarily used as a toy for children the material is also used therapeutically for stress reduction. In the home it can be used to pick up dirt, lint, and pet hair, and because of its adhesive characteristics it was even used by Apollo astronauts to secure their tools in zero-gravity.