Roller skating

Roller skating is the traveling on surfaces with roller skates. It is a form of recreational activity as well as a sport, and can also be a form of transportation. In fact, as the United States readied for World War II, the government entertained the notion to add roller skates as essential equipment to move infantry around Europe to save gas. Skates generally come in three basic varieties: quad roller skates, inline skates or blades and tri-skates, ... Source : https://en.wikipedia.org/wiki/Roller_skating