There are several different Playoff formats used in various levels of competition in sports and games. Some of the most common are the single elimination, the best-of- series, the total points series, and the round-robin tournament.
Single elimination[]
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. 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. Six teams are seeded from each conference, with the top two getting a first-round "bye" (a free pass to the second round). The remaining teams pair off, with the higher-seeded team hosting. The winners play the teams that received byes, and the winners of those matches face each other to determine who will represent each conference in the Super Bowl. The winner of that game wins the championship.
In both the men's and women's NCAA college basketball tournaments, 64 teams are seeded into four brackets of 16 teams each. (On the men's side, the 64th place team and a 65th team play each other in a play-in game to determine the final participant.) The #1 team plays the #16 team in each bracket, the #2 plays the #15, and so on. Theoretically, if a higher ranked team always beats a lower ranked team, the second game will be arranged #1 vs. #8, #2 vs. #7, etc.; the third will be arranged #1 vs. #4, #2 vs. #3; the fourth will be arranged #1 vs. #2. If for instance #9 beats #8 in the first game, the #9 will simply take the theoretical spot of #8 and play #1. Winners advance through each round, changing cities after every two rounds. The Final Four teams, one from each bracket, play each other in the last weekend, with the winner of the final two being awarded the championship.
Association football often uses single elimination to determine finalists and winners. Major League Soccer's second and final rounds of its playoffs use a single elimination format, though the first round is a total points format. The FIFA World Cup also uses knockout rounds after a group stage of 32 teams divided into 8 groups of 4 determines who advances to them.
Double elimination[]
A double elimination format is used in most NCAA and high school baseball and softball tournaments in the United States.
The format changes depending on the number of teams per bracket, but most major collegiate baseball conferences with the format send only the top eight teams, or a mix of top teams plus the winners of a single elimination qualifier tournament, to their conference tournament.
The NCAA baseball and softball tournaments have used the format since its inception for regional and College World Series play.
In the current NCAA tournament format for four teams, the #1 seed plays the #4 seed ("Game 1"), and the #2 seed plays the #3 seed ("Game 2") on the first day of regional tournaments, and the first and second days of the College World Series (where the second bracket games are known as "Game 3" and "Game 4", respectively).
On the second day or series (third and fourth days at the College World Series), the losers play in the morning to determine who is eliminated ("Game 3" in regional, "Games 5" and "Game 7" in College World Series play), and who advances to the third game of the day. The winners ("Game 4" in regional, "Game 6" and "Game 8" in College World Series) play to determine who advances to the final on the third day.
In NCAA regional games, the loser of this game plays the winner of the morning game that evening ("Game 5") to determine who plays in the final.
In College World Series play, because the bracket teams play on alternating days, these games ("Game 9" and "Game 10") are played on the fifth day.
In NCAA regional games, the third day will feature the regional championship ("Game 6"). If the winner of Game 4 defeats the winner of Game 5, the winner advances to the Super Regional. Until the 2005 tournament, if the winner of Game 5 defeats the winner of Game 4, the two teams would meet again in Game 7 thirty minutes later to determine which team advances to the Super Regional.
However, with a concern that some teams were playing four games in two days, the NCAA made a rule change in 2005 to equalise the disadvantage of the winner of Game 5 by stating should the winner of Game 5 win Game 6, Game 7 would be played on a fourth day.
In the College World Series, on the sixth day, the winner of Game 9 plays the winner of Game 7 ("Game 11"), and the winner of Game 10 plays the winner of Game 8 ("Game 12"). If the winner in Game 7 wins Game 11, and/or the winner of Game 8 wins Game 12, such winners advance to the best-of-three final. If the winner of Game 9 defeats the winner of Game 7, and/or the winner of Game 10 defeats the winner of Game 8 the two teams would play again on the seventh day in Games 13 and 14, respectively, if they are needed, to determine who advances to the final.