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. Skates generally come in three basic varieties: quad roller skates, inline skates or blades and tri-skates, 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, first between 1935 and the early 1960s and then in the 1970s, when polyurethane wheels were created and "Disco" oriented roller rinks were the rage and then again in the 1990s when in-line outdoor roller skating, thanks to the improvement made to inline roller skates in 1981 by Scott Olson, took hold.
During the late 1980s and early 1990s, the Rollerblade-branded skates became so successful that they inspired many other companies to create similar inline skates, and the inline design became more popular than the traditional quads. The Rollerblade skates became synonymous in the minds of many with "inline skates" and skating, so much so that many people came to call any form of skating "Rollerblading," thus making it a genericized trademark.
For much of the 1980s and into the 1990s, inline skate models typically sold for general public use employed a hard plastic boot, similar to ski boots. In or about 1995, "soft boot" designs were introduced to the market, primarily by the sporting goods firm K2 Inc., and promoted for use as fitness skates. Other companies quickly followed, and by the early 2000s the development of hard shell skates and skeletons became primarily limited to the Aggressive inline skating discipline and other specialized designs.
The single-wheel "quintessence skate" was made in 1988 by Miyshael F. Gailson of Caples Lake Resort, California, for the purpose of cross-country skate skiing and telemark skiing training. Other experimental skate designs the years have included two wheeled (heel and toe) inline skate frames but the vast majority of skates on the market today are either quad or standard inline design.