A Slinky is a precompressed helical spring toy invented by Richard James in the early 1940s. It can perform a number of tricks, including travelling down a flight of steps end-over-end as it stretches and re-forms itself with the aid of gravity and its own momentum, or appear to levitate for a period of time after it has been dropped. These interesting characteristics have contributed to its success as a toy in its home country of the United States, resulting in many popular toys with slinky components in a wide range of countries.

https://en.wikipedia.org/wiki/Slinky