A skateboard is a narrow wheeled platform used for the activity of skateboarding. Though the exact date of invention of skateboards is unknown, it was in the 1940s and 1950s that children participated in soap box derbys where they would race soap-boxes attached to wooden planks on rollerskate wheels. During events like this, some of the soap-boxes became detached from the planks, leaving the rider with what was a skateboard.