Roller derby is a sport played on roller skates. It used to be played by both men and women, but it was restarted by women. There are now a growing number of men's and mixed (or co-ed) teams around the world who are playing roller derby.
For a long time, many people did not believe roller derby was a real sport. They thought it was like professional wrestling, because it had fake fighting and other things for TV. But in 2002, a group of women in Austin, Texas started playing it as a real game, with nothing fake. A TV show called Rollergirls was made about some of these women. By 2006, women in every big city in the USA and Canada were starting their own roller derby clubs. There were even clubs starting up in Europe, Australia, and New Zealand.