A tournament is a competition involving at least three competitors, all participating in a sport or game. More specifically, the term may be used in either of two overlapping senses:

1. One or more competitions held at a single venue and concentrated into a relatively short time interval.
2. A competition involving a number of matches, each involving a subset of the competitors, with the overall tournament winner determined based on the combined results of these individual matches. These are common in those sports and games where each match must involve a small number of competitors: often precisely two, as in most team sports, racket sports and combat sports, many card games and board games, and many forms of competitive debating. Such tournaments allow large numbers to compete against each other in spite of the restriction on numbers in a single match.

These two senses are distinct. All golf tournaments meet the first definition, but while match play tournaments meet the second, stroke play tournaments do not, since there are no distinct matches within the tournament. In contrast, association football leagues like the Premier League are tournaments in the second sense, but not the first, having matches spread across many venues over a period of up to a season. Many tournaments meet both definitions; for example, the Wimbledon tennis championship. Tournaments "are temporally demarcated events, participation in which confers levels of status and prestige amongst all participating members".

A tournament-match (or tie or fixture or heat) may involve one or more game-matches (or rubbers or legs) and if necessary one or more tiebreak-matches between the competitors. For example, in the Davis Cup tennis tournament, a tie between two nations involves five rubbers between the nations' players. The team that wins the most rubbers wins the tie. In the later rounds of UEFA Champions League, each fixture is played over two legs. The scores of each leg are added, and the team with the higher aggregate score wins the fixture, with extra time, and if necessary, a penalty shoot-out used if the scores are level after both matches conclude. In this case, the first tiebreak-match is extra time (modified game-match with reduced duration) and the second tiebreak-match is a penalty shoot-out.