Netball is a ball sport played on a rectangular court by two teams of seven players. The primary objective is to shoot a ball ( in circumference) through the defender's goal ring ( in diameter mounted high to a goal post at each end of the court) while preventing the opposing team from shooting through their own goal ring. It is one of a few sports created exclusively for women and girls and remains primarily played by them, on indoor and outdoor courts, especially in schools and most popularly in the Commonwealth of Nations. According to World Netball, the sport is played by more than 20 million people in more than 80 countries. World Netball comprises more than 70 national teams organized into five global regions. Major domestic leagues in the sport include the Netball Superleague in Great Britain, Suncorp Super Netball in Australia and the ANZ Premiership in New Zealand. Four major competitions take place internationally: the quadrennial World Netball Championships, the Commonwealth Games, and the yearly Quad Series and Fast5 Series. In 1995, netball became an International Olympic Committee recognised sport federation, but it has not been played at the Olympics. A common misunderstanding of netball's origins has resulted in the mistaken belief that netball was created to prevent women from playing basketball. Its development traces back to American sports teacher Clara Gregory Baer's misinterpretation of the basketball rule book in 1895. The book had lines of patrol drawn on it and Clara interpreted this to mean that players had to stay in those zones. Baer's modifications proliferated and were later officially ratified into the rules for women's basketball by 1899. Martina Bergman-Österberg had also introduced basketball to her female students at her Physical Training College in England in 1893. In the beginning it was also described as "women's basketball" but by 1897 it started to evolve into a distinctly separate sport based on modifications developed at Bergman-Österberg's college combined with Baer's rules.