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 and Major League Baseball use this system, and MLB uses it only in the first round, and only wildcard teams face this single elmination round (all division winners receive a bye through the first round, automatically advancing to the division series). The NFL uses this system throughout its playoffs. 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. 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.
In both the men's and women's NCAA college basketball tournaments, 64 teams are seeded into four brackets of 16 teams each. (From 2011, the men's tournament will feature a "First Four", with the four lowest-ranked conference champions and the four lowest-seeded at-large teams playing single games to enter the 64-team draw.) 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.
National association football competitions usually don't have playoffs, but when employed, use single-elimination formats to determine finalists and winners. The Major League Soccer playoffs use such a format; since 2012, the first round in each conference and the championship final, known as the MLS Cup, are conducted as single games, while the conference semifinals and conference finals are two-legged matches determined on total goals scored. Liga MX in Mexico, which splits its season into two phases, uses playoffs known as the Liguilla to determine the champions of each phase. Unlike the MLS system, all Liguilla matches are two-legged ties. Australia's A-League introduced a six-team knockout playoff, known locally as a "finals series", in the 2012–13 season. Unlike the MLS playoffs or Liga MX Liguilla, the A-League finals series uses one-off matches throughout, culminating in the A-League Grand Final. This format is a departure from norms in football codes in Australia; previously, the A-League used a hybrid elimination system that allowed top teams in the regular season to lose one finals match but still win the tournament. The FIFA World Cup tournament also uses knockout rounds after a group stage of 32 teams divided into 8 groups of 4 determines who advances to them.
Some knockout tournaments may also include a third place playoff, a single match to decide which competitor or team will be credited with finishing third and fourth place. The teams that compete in such third place games are usually the two losing semifinalists in a particular tournament. Although these semifinalists are still in effect "eliminated" from contending for the championship, they either may be competing for a bronze medal like some tournaments in the Olympic Games or basically just to salvage some pride in a consolation match, like in the FIFA World Cup or Rugby World Cup.
Read more about this topic: Playoff Format