BMX racing is a type of off-road bicycle racing. The format of BMX was derived from motocross racing. BMX bicycle races are sprint races on purpose-built off-road single-lap race tracks. The track usually consists of a starting gate for up to eight racers, a groomed, serpentine, dirt race course made of various jumps, and a finish line. The course is banked and has flat corners. The sport of BMX racing is facilitated by a number of regional and international sanctioning bodies. They provide rules for governing the conduct of the races, specify age-group and skill-level classifications among the racers, and maintain some kind of points-accumulation system over the racing season. The sport is largely participant-driven, with the average age of approximately 9 or 10 years. Professional ranks exist for both men and women, where the average age is 18 to 21.