Roller skating is an activity or sport in which people strap on roller skates, shoes with four small wheels on them, and push laterally and backwards with alternating skates while gliding on the other. This is often done in a roller skating rink with smooth plastic floors which allow for sideways sliding motions to be incorporated into roller skate dance moves. Alternatively, roller skating may be engaged in out of doors on streets or sidewalks, and includes long distance races on in-line roller skates as well as outdoor roller skate dancing, or jam skating. Roller hockey is another form of roller skating. A small competitive figure roller skating circuit exists in the US as well.