[2] The game revolves around two teams of five players taking turns playing offense and defense, with each of the offensive team's players taking turns hitting a small rubber ball with their bare hands into the field of play (which is a 21 m (68.90 ft)-square),[3] and then running counterclockwise around four bases (13 m (42.65 ft) apart) laid out in a square shape to score a run, while the defensive team tries to eliminate ("get out") offensive players before they complete their trip around the bases to prevent them from scoring.

Oftentimes, a best-of-three (or even best-of-five) series of "sets" is played to determine the result of a matchup between two teams.

[12][13][14] The game is also scheduled to be played in a mixed-gender format at the 2026 Summer Youth Olympics,[15] and has started to find adoption in schools, national championships, and other international events around the world.

[16][17][18][19][20] B5 was inspired by similar games that have been played on the streets in Latin America and elsewhere for decades, such as cuatro esquinas (four corners) in Cuba[21] and pelotica de goma (little rubber ball)[22] in Venezuela.

[11][23] In some cases, B5 significantly diverges from the rules of these games;[24] for example, it does not feature a pitcher, as is done in one street variation in Colombia,[25] and players are allowed to run the bases, as opposed to only walking, as is required in one version of "cuatro esquinas".

[27] B5 was invented in part to increase the odds that a sport similar to baseball and softball will be played in the Olympics,[28] with B5 meant to contribute to an ultimate goal of having a billion fans in the baseball-softball community by 2030[29][30][31] and helping to demonstrate the global reach of the games.

[35] In this respect, as well as the fact that there are fewer players required to play a game,[36] B5 is meant to imitate smaller, more urban variants of other major sports, such as 3x3 basketball, futsal, and rugby sevens.

[37] Another claimed benefit is that with B5 being introduced across the entire world at the same time, no one country is likely to dominate the game;[43] the lack of the pitcher role, which is highly specialized, contributes to this.

[48][49] The WBSC has tried to promote B5 for socially beneficial purposes as well, by taking it to places such as Jordan's Azraq refugee camp.

[27] Before the 2022 Baseball5 World Cup, a new B5 rulebook was published that increased clarity on some of the rules, as well as changing some of the field dimensions.

Ideal shape and size of the first three bases is a 60 cm (23.62 in)-square, and they are placed in the outfield (the part of fair territory outside of the infield).

However, every league or tournament organisation may decide on other ways of limiting the field of play, such as using existing walls or marking the ground with lines.

When scoring, a runner may step on the batter's box instead of home plate in order to avoid collisions.

[68][13] The 2025 YB5WC will act as a qualifier for the mixed-gender Baseball5 event to be held in the Dakar 2026 Youth Olympic Games (YOG).