Bo3 is short for best of three. It refers to a series in which two teams play each other until one of them reaches two wins. If one team wins the first two maps, the third is not played. If the score becomes 1:1, a deciding map is played.
How it works
A series lasts three maps at most and two at minimum. The possible final scores are:
- 2:0 — the winner took both of the first two maps, so the third is not needed;
- 2:1 — the teams traded wins, and the third map decided everything.
The word "map" here means one complete game on a chosen location. In games where a match consists of rounds, such as CS2, a map is a separate segment of the series with its own round score. In games without rounds, such as Dota 2, the same role is played by one full game. That is why the Bo3 format is used in both kinds of titles, and across esports as a whole the principle is the same: whoever first wins the majority of games wins the series.
Why organizers like Bo3
The format is considered a golden mean between two extremes:
- Bo1 — a single game, where the outcome depends heavily on chance: one unlucky map and a strong team is knocked out;
- Bo5 — up to five games, which gives the most accurate result, but the series can run for several hours.
Bo3 gives a team the chance to fix a mistake and come back into the series after a loss, while still taking a reasonable amount of time and fitting neatly into a broadcast schedule. That is why most tournaments use Bo3 in the playoffs and in many group stages, while Bo5 is more often reserved for the most important matches.
Map selection in a series
In games with a map pool, a Bo3 series almost always includes a selection procedure: teams take turns banning the maps they do not want to play and picking the ones where they feel more confident. The exact order depends on the tournament rules, so it is always worth checking the competition's regulations. This procedure is what makes Bo3 more interesting for viewers: you can see how a team prepares for its opponent and guess which maps it will be strong on.
How the term is used
Among English-speaking fans, the term is usually pronounced "B-O-three" or simply "best of three." In texts and in tournament brackets it is most often written as Bo3. Typical phrases: "the match will be played as a Bo3," "in the playoffs, all series are played to two wins," "to lose a Bo3 0:2."
For a team, Bo3 is also a matter of strategy: you have to decide which map to pick first, which one to save for the deciding game, and how to survive a bad start. For viewers, the format provides drama: a 1:1 score and a decisive third map usually become the most tense moment of the series.