A round-robin tournament is a competition in which every competitor faces every other competitor. A well-known example of a round-robin tournament is the FIFA World Cup group stage, in which each of the four teams in a single group play each other.
The term "round robin" comes from the French phrase "ruban," which means "ribbon." In a single round-robin tournament, like the FIFA World Cup group stage, each competitor plays each of the other competitors once. In a double round-robin tournament, each competitor plays each of the other competitors twice. A round-robin tournament is an alternative to an elimination tournament, in which competitors only play one or more of the other competitors in the tournament.
While an elimination tournament is more efficient and can be completed more quickly, the round-robin tournament is more likely to have the best competitor emerge victorious because it features a larger competitive sample size. Further, while an elimination tournament can be decided based on individual matchups, a round-robin tournament ensures that the competitor who is most successful against all other competitors emerges victorious. Yet, round-robin tournaments are often disfavored because the number of rounds must be one less than the total number of competitors in order to ensure that every competitor plays every other competitor.