Rules of The Game

History

Unlike many other sports, the Official Baseball Rules have remained mainly static during the modern era of the game. Many baseball players, fans and administrators view the rules and traditions of professional baseball as time-tested and nearly sacrosanct.

This was not the case during baseball's early days, particularly in the late 19th century, when rules were changed significantly and often yearly. The modern game began to take shape in the late 1880s, with additional significant rule changes made during the rest of that century.

Throughout baseball's history, the rules have frequently changed as the game continues to evolve. A few typical rules most professional leagues have in common are that four balls are a base on balls, three strikes are a strikeout, and three outs end a half-inning.

Baseball evolved out of bat-and-ball games in the mid-19th century, and its modern rules are based mainly on those first published in 1848. Most rule sets are generally based on the Official Baseball Rules (OBR) published by Major League Baseball (MLB), though various minor variations exist from league to league; the World Baseball Softball Confederation maintains its own official rule set for international competition.

The Official Baseball Rules, published by Major League Baseball, govern all professional play in the United States and Canada. Many amateur and youth leagues use the OBR with only a few modifications for safety, including Little League, PONY League, and Cal Ripken League. Most professional leagues outside North America (such as Japan's Nippon Professional Baseball) also use modified versions of the OBR, though these generally have more pronounced differences.

The World Baseball Softball Confederation (WBSC), which governs international tournaments like the Summer Olympics, Baseball World Cup, and WBSC Premier 12, first published its own official rule set in 2023; the WBSC had previously relied on a modified set of the OBR. WBSC rules are largely similar to the OBR, with minor differences including pitch clock timing and extra-innings tiebreakers. These rules do not apply to the World Baseball Classic, which is organized jointly by the WBSC and MLB.

The baseball rulebook of the National Collegiate Athletic Association (NCAA), aside from governing the games of that organization's members, is also used by several other competitions involving college-aged players.

The rules of the National Federation of State High School Associations (NFHS) hold sway over U.S. high school and high school-age baseball, governing and shaping the sport at this level.