Olympic sports
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).
Olympic sports
Previous Olympic Games included sports that are no longer included in the current program, such as polo and tug of war. Known as "discontinued sports", these have been removed due to either a lack of interest or the absence of an appropriate governing body for the sport. Some sports that were competed at the early Games and later dropped by the IOC, have managed to return to the Olympic program, for example Archery, which made a come-back in 1972, and tennis, which was reintroduced in 1988. The Olympics have often included one or more demonstration sports, normally to promote a local sport from the host country or to gauge interest in an entirely new sport. Some such sports, like baseball and curling, were added to the official Olympic program (in 1992 and 1998, respectively). Baseball was discontinued after the 2008 Olympics in Beijing, only to be revived again for the forthcoming 2020 Olympics in Tokyo, which will see the introduction of new disciplines within a number of existing Summer Olympics sports as well as several new sports, such as karate and skateboarding, making their Olympic debuts.