Best-of-seven

There are a number of formats used in various levels of competition in sports and games to determine an overall champion. Some of the most common are the single elimination, the best-of- series, the total points series, and the round-robin tournament.

A Single elimination ("knockout") playoff pits the participants in one-game matches, with the loser being dropped from the competition. Single elimination tournaments are much more common in individual sports like tennis. In most tennis tournaments, the players are seeded against each other, and the winner of each match continues to the next round, all the way to the final.

Of the big four American sports leagues, only the National Football League uses this system for all rounds of its postseason. This works for the NFL because its regular seasons are much shorter (16 games) than those in the other sports (from 82 to 162 games), and the difference in quality between teams is believed to be more quickly discernible. The rigors of individual games, held only once per week, also preclude the possibility of longer playoff series. Since the 1990 season six teams are seeded from each conference, with the top two getting a first-round "bye". The remaining teams pair off, with the higher-seeded team hosting. The winners of those games then play the higher-seeded teams that received byes in elimination playoffs, and then the winners of those matches face each in another in elimination playoffs to determine who will represent each conference in the Super Bowl. The winner of that game wins the championship.

Until the late 1960s, the only regular post-season fixtures in U.S. professional football were the league Championship Games. Divisional playoffs were only held in the event of a tie in the division standings. Divisional playoffs as a regularly scheduled event were not introduced in the NFL and rival American Football League until the seasons immediately preceding the AFL-NFL merger in 1970.

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