page_title: Baseball rules
section_title: General structure
hierarchical_section_title: Baseball rules / Gameplay / General structure
context_page_description: The rules of baseball differ slightly from league to league, but in general share the same basic game play.
context_section_description: Baseball is played between two teams with nine players in the field from the team that is not batting at that point (the batting team would have one batter in play at "home plate" on the field). On a baseball field, the game is under the authority of several umpires. There are usually four umpires in major league games; up to six (and as few as one) may officiate depending on the league and the importance of the game. There are three bases. Numbered counterclockwise, first, second, and third bases are cushions (sometimes informally referred to as bags) shaped as 15 in (38 cm) squares which are raised a short distance above the ground; together with home plate, the fourth "base", they form a square with sides of 90 ft (27.4 m) called the diamond.  Home plate is a pentagonal rubber slab 17 in (43.2 cm) wide. The playing field is divided into three main sections:
  The infield, containing the four bases, is for general defensive purposes bounded by the foul lines and within the grass line (see figure).
  The outfield is the grassed area beyond the infield grass line between the foul lines, and bounded by a wall or fence.
  Foul territory is the entire area outside the foul lines.
  The pitcher's mound is located in the center of the infield. It is an 18 ft (5.5 m) diameter mound of dirt no higher than 10 in (25.4 cm). Near the center of the mound is the pitching rubber, a rubber slab positioned 60 ft 6 in (18.4 m) from home plate. The pitcher must have one foot on the rubber at the start of every pitch to a batter, but the pitcher may leave the mound area once the ball is released.
  At the college/professional level, baseball is played in nine innings in which each team gets one turn to bat and tries to score runs while the other pitches and defends in the field. High school baseball plays seven innings and Little League uses six-inning games. An inning is broken up into two halves in which the away team bats in the top (first) half, and the home team bats in the bottom (second) half. In baseball, the defense always has the ball—a fact that differentiates it from most other team sports. The teams switch every time the defending team gets three players of the batting team out. The winner is the team with the most runs after nine innings. If the home team is ahead after the top of the ninth, play does not continue into the bottom half. When this happens, an X is put on the scoreboard for the home team's score in the ninth inning. In the case of a tie, additional innings are played until one team comes out ahead at the end of an inning. If the home team takes the lead anytime during the bottom of the ninth or of any inning after that, play stops and the home team is declared the winner. This is known as a walk-off.
  The basic contest is always between the pitcher for the fielding team and a batter. The pitcher throws—pitches—the ball towards home plate, where the catcher for the fielding team waits (in a crouched stance) to receive it. Behind the catcher stands the home plate umpire. The batter stands in one of the batter's boxes and tries to hit the ball with a bat. The pitcher must keep one foot in contact with the top or front of the pitcher's rubber—a 24×6 in (61×15 cm) plate located atop the pitcher's mound—during the entire pitch, so he can only take one step backward and one forward in delivering the ball. The catcher's job is to receive any pitches that the batter does not hit and to "call" the game by a series of hand movements that signal to the pitcher what pitch to throw and where. The catcher also usually signals the desired location of the ball within the strike zone and "sets up" behind the plate or holds his glove up in the desired location as a target.  The catcher's role becomes more crucial depending on how the game is going, and how the pitcher responds to a given situation. Each pitch begins a new play, which might consist of nothing more than the pitch itself.
  Each half-inning, the goal of the defending team is to get three members of the other team out. A player who is out must leave the field and wait for his nex
caption: A batter follows through after swinging at a pitched ball.
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