What is Roller Derby?

Roller derby is a fast-moving contact sport played by two teams of five members on quad skates moving in the same direction around a track. A bout is made up of a series of short match ups (jams) in which both teams designate a jammer who scores points by lapping members of the opposing team, and four blockers who attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing both offense and defense simultaneously.

Watch it all in motion: