Roller skating is the traveling on smooth surfaces with roller skates. It is a form of recreation as well as a sport, and can also be a form of transportation. Skates generally come in two basic varieties: quad roller skates and inline skatesor blades, though some have experimented with a single-wheeled “quintessence skate” or other variations on the basic skate design. In America, this hobby was most popular in the 1970s and the 1990s.
Reference: Wikipedia Roller Skating