Roller derby is a fun, fast paced contact sport played worldwide by two teams of fifteen members wearing quad skates, on a flat, oval track. Play is broken up into two 30 minute periods, and within those periods, into units of play called jams, which last up to two minutes. There are 30 seconds between each jam.

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During a jam, each team fields up to five skaters. Four of these skaters are called blockers (together, the blockers are called the pack), and one is called a jammer. The jammer wears a helmet cover with a star on it. 

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The two jammers start each jam behind the pack, and score a point for every opposing blocker they lap, each lap. Because they start behind the pack, they must get through the pack, then all the way around the track to be eligible to score points on opposing blockers. 

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The teams attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing  both offense and defense simultaneously. Roller derby is a full-contact sport, however skaters cannot use their heads, elbows, forearms, hands, knees, lower legs, or feet to make contact to opponents. Skaters cannot make contact to opponents’ heads, backs, knees, lower legs or feet.

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Roller derby is an international sport with mostly all-female teams, though there is a growing number of male, unisex and junior roller derby teams.

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Rocky Mountain Rollergirls have absolutely nailed a simple and speedy blow-by-blow run down of the game in this video: 

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