National Hockey League in the United States and Canada is the top-tier ice hockey league in the world. Despite not having worldwide fan-following, NHL is the fifth-wealthiest of all professional sports leagues in the world. The Stanley Cup awarded to the winners of the league is the oldest sports trophy in North America. The league started with four teams all from Canada and later expanded to the US. The first six teams including two from the US are nicknamed the "Original Six".
Professional ice hockey has two standard sets of rules, the NHL's rules are one of them. The rules have been modified from time to time. For instance, penalty shots were not part of NHL games but were later adopted from the Pacific Coast Hockey Association. Some major changes pertaining to offside were made in the 2005-06 season. The "two-line pass" rule was removed while the "tag-up offside" rule was reinstated with the objective of increasing overall scoring which was in decline. NHL rules differ from those of the International Ice Hockey Federation (IIHF). Tournaments like the Olympics follow the latter's rules.
A season of the NHL starts with preseason games that begin in September and run until early October. The regular season runs from early October to mid-April after which start the postseason games, also known as the Stanley Cup playoffs. Every team in the league plays 82 matchups in the regular season, 41 at home and 41 on the road. A team will play 26 of its games in its own geographical division. A win earns a team two points while an overtime/shootout loss gives a point. The team with the most points in a division becomes the divisional champions as the regular season ends. In the playoffs, two sides are pitted against each other in a best-of-seven series and the winner makes it to the next round. The last team that remains becomes the Stanley Cup champions.