Swiss system tournament

A Swiss-system tournament is a non-eliminating tournament format which features a set number of rounds of competition, but considerably fewer than in a round-robin tournament. In a Swiss tournament, each competitor (team or individual) does not play every other. Competitors meet one-to-one in each round and are paired using a set of rules designed to ensure that each competitor plays opponents with a similar running score, but not the same opponent more than once. The winner is the competitor with the highest aggregate points earned in all rounds. All competitors play in each round unless there is an odd number of them.

A Swiss system is used for competitions with a large number of entrants, so that a full round-robin is not feasible, but it is not desired to eliminate any competitors before the end of the tournament. Round-robin pairings are suitable for a small number of competitors and rounds, as most or all players will play each other; the underlying assumption is that the player who has played all possible opponents and ends with the highest score, must be the winner. Knockout, or elimination, pairings rapidly reduces the number of competitors, but may not necessarily result in the best possible competitor winning, as good competitors might have a bad day or eliminate and exhaust each other if they meet in early rounds. Swiss systems intend to provide a clear winner with a limited number of rounds and a potentially unlimited number of opponents. A Swiss system draw should result in a clear winner, without having to play all opponents as in round robin, and without a single bad result terminating participation.

The first tournament of this type was a chess tournament in Zurich in 1895, hence the name "Swiss system". Swiss systems are commonly used in chess,bridge, eSports, Morabaraba, Scrabble, Backgammon, squash, Pétanque (boules), Quiz bowl, Magic: The Gathering,Policy Debate, Warhammer, eight-ball, Reversi, Dominion, Pokémon TCG,Yu-Gi-Oh,Blood Bowl, Star Wars: X-Wing Miniatures Game, Path of Exile and Android: Netrunner.

...
Wikipedia