Ice hockey is a contact team sport played on ice, usually in a rink, in which two teams of skaters use their sticks to shoot a vulcanized rubber puck into their opponent's net to score goals. The sport is known to be fast-paced and physical, with teams usually fielding six players at a time: one goaltender, and five players who skate the span of the ice trying to control the puck and score goals against the opposing team. Ice hockey is most popular in Canada, central and eastern Europe, the Nordic countries, Russia, and the United States. Ice hockey is the official national winter sport of Canada. In addition, ice hockey is the most popular winter sport in Belarus, Croatia, the Czech Republic, Finland, Latvia, Russia, Slovakia, Sweden, and Switzerland. North America's National Hockey League (NHL) is the highest level for men's ice hockey and the strongest professional ice hockey league in the world. The Kontinental Hockey League (KHL) is the highest league in Russia and much of Eastern Europe. The International Ice Hockey Federation (IIHF) is the formal governing body for international ice hockey, with the IIHF managing international tournaments and maintaining the IIHF World Ranking. Worldwide, there are ice hockey federations in 76 countries. In Canada, the United States, Nordic countries, and some other European countries the sport is known simply as hockey; the name "ice hockey" is used in places where "hockey" more often refers to field hockey, such as countries in South America, Asia, Africa, Australasia, and some European countries including the United Kingdom, Ireland and the Netherlands. Ice hockey is believed to have evolved from simple stick and ball games played in the 18th and 19th centuries in the United Kingdom and elsewhere. These games were brought to North America and several similar winter games using informal rules were developed, such as shinny and ice polo. The contemporary sport of ice hockey was developed in Canada, most notably in Montreal, where the first indoor hockey game was played on March 3, 1875. Some characteristics of that game, such as the length of the ice rink and the use of a puck, have been retained to this day. Amateur ice hockey leagues began in the 1880s, and professional ice hockey originated around 1900. The Stanley Cup, emblematic of ice hockey club supremacy, was first awarded in 1893 to recognize the Canadian amateur champion and later became the championship trophy of the NHL. In the early 1900s, the Canadian rules were adopted by the Ligue Internationale de Hockey Sur Glace, the precursor of the IIHF and the sport was played for the first time at the Olympics during the 1920 Summer Olympics. In international competitions, the national teams of six countries (the Big Six) predominate: Canada, Czech Republic, Finland, Russia, Sweden and the United States. Of the 69 medals awarded all-time in men's competition at the Olympics, only seven medals were not awarded to one of those countries (or two of their precursors, the Soviet Union for Russia, and Czechoslovakia for the Czech Republic). In the annual Ice Hockey World Championships, 177 of 201 medals have been awarded to the six nations. Teams outside the Big Six have won only five medals in either competition since 1953. The World Cup of Hockey is organized by the National Hockey League and the National Hockey League Players' Association (NHLPA), unlike the annual World Championships and quadrennial Olympic tournament, both run by the International Ice Hockey Federation. World Cup games are played under NHL rules and not those of the IIHF, and the tournament occurs prior to the NHL pre-season, allowing for all NHL players to be available, unlike the World Championships, which overlaps with the NHL's Stanley Cup playoffs. Furthermore, all 12 Women's Olympic and 36 IIHF World Women's Championship medals were awarded to one of these six countries. The Canadian national team or the United States national team have between them won every gold medal of either series.