A slinky is a popular toy made of a flexible metal or plastic coil that can stretch and spring back into its original shape. It was invented in the early 1940s by Richard James, a mechanical engineer. The slinky can walk down stairs, perform tricks, and create interesting visual effects when manipulated. When a slinky is held at one end and released, it creates a wave-like motion as it moves down steps or surfaces. This unique movement is due to the tension and gravity acting on the coil. Slinkies are often used in educational settings to demonstrate principles of physics, such as energy transfer and wave motion.