Olympic sports are contested in the Summer Olympic Games and Winter Olympic Games. The 2016 Summer Olympics included 28 sports, with five additional sports due to be added to the 2020 Summer Olympics program; the 2014 Winter Olympics included seven sports. The number and types of events may change slightly from one Olympiad to another. Each Olympic sport is represented by an international governing body, namely an International Federation (IF). The International Olympic Committee (IOC) establishes a hierarchy of sports, disciplines, and events. According to this hierarchy, each Olympic sport can be subdivided into multiple disciplines, which are often mistaken as distinct sports. Examples include swimming and water polo, which are in fact disciplines of the sport of aquatics (represented by the International Swimming Federation), and figure skating and speed skating, which are both disciplines of the sport of ice skating (represented by the International Skating Union). In turn, disciplines are subdivided into events, for which Olympic medals are awarded. A sport or discipline is included in the Olympic program if the IOC determines it to be widely practised around the world, that is, the popularity of a given sport or discipline is indicated by the number of countries that compete in it. The IOC's requirements also reflect participation in the Olympic Games – more stringent conditions are applied to men's sports/disciplines (as men are represented at the Games in higher numbers than women) and to summer sports/disciplines (as more nations compete in the Summer Olympics than in the Winter Olympics).