Roller derby is a contact sport played by two teams. Game play consists of a series of short matchups (”jams”) in which both teams field five members each roller skating in a counter clockwise direction around a track. Each team designate a scoring player (the ”jammer”) who scores points by lapping members of the opposing team.
There is flat track roller derby and banked track roller derby. Crime City Rollers is a flat track roller derby league. Flat track roller derby is a fast-paced contact team sport that requires speed, strategy, and athleticism. The flat track version of the sport evolved in 2001, and has quickly grown to encompass more than 400 leagues worldwide. This is in large part due to the ease of setting up a flat track–it can be done on any flat surface that is suitable for skating, such as skating rinks, basketball courts, parking lots, and even airplane hangars. This greatly reduces the capital needed to start up a roller derby league, and allows small groups of people to get a fledgling league off the ground. The DIY spirit that drives the sport allows roller derby leagues to create their own unique identities and adapt their structures to reflect their local communities
Most current roller derby leagues use rules developed by the Women’s Flat Track Derby Association (WFTDA).
You can read all the rules here: https://rules.wftda.com/