The Ice Hockey World Championships is an annual event held by the International Ice Hockey Federation (IIHF). It was preceded by the European Championship which was held from 1910 to 1932. The first World Championship tournament was decided at the 1920 Summer Olympics. Subsequently, ice hockey was featured at the Winter Olympic Games, where the World Championship was decided when the two events occurred concurrently, until the 1968 Winter Olympics. The first three championships were contested at the Olympics, while the first World Championships that were an individual event were held in 1930.
The modern format for the World Championship features 16 teams in the championship group, 12 teams in Division I and 12 teams in Division II. If there are more than 40 teams, the rest compete in Division III. The teams in the championship play a preliminary and qualifying round, then the top eight teams play in the playoff medal round and the winning team is crowned World Champion. From the 1920 Olympics until the 1976 World Championships, only athletes designated as 'amateur were allowed to compete in the tournament. Because of this, players from the National Hockey League were not allowed to compete, while full-time players of the Soviet Union were allowed. In 1970, after an agreement to allow its professionals to participate was rescinded by the IIHF, Canada withdrew from the tournament. Starting in 1977, professional athletes were allowed to compete in the tournament and Canada re-entered.
As of 2016, 81 tournaments have been staged. From 1920 to 1930, the Winter Olympic Games Ice Hockey Tournaments held counted as the World Championships and no tournaments in between were held. No championships were held from 1940 to 1946 due to World War II, nor during the Olympic years 1980, 1984 and 1988. Ten nations have won a gold medal at the World Championships and a total of fourteen have won medals. Canada has won 48 medals, the most of any nation. The Soviet Union, which began competing in 1954 and last competed in 1991, captured a medal in every tournament they entered. In winning the 2006 World Championships, Sweden became the first nation in sports history to win an Olympic gold as well as a separate World Championship in the same season.