Roller derby is a contact sport played by two teams of five members roller skating counter-clockwise around a track. Roller derby is played by approximately 1,250 leagues worldwide.
Game play consists of a series of short match-ups (jams) in which both teams designate a jammer (who wears a star on the helmet). The jammer scores points by lapping members of the opposing team. The teams attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing both offense and defense simultaneously.
The Women’s Flat Track Derby Association (WFTDA) is the international governing body for the sport of women’s flat track roller derby. The organization was founded in April 2004 as the United Leagues Coalition (ULC), but was renamed in November 2005. It is registered as a business league organization, which is a type of non profit organization. WFTDA sets “standards for rules, seasons, and safety, and determining guidelines for the national and international athletic competitions of member leagues”, and says “all member leagues have a voice in the decision-making process, and agree to comply with WFTDA policies”.