Gameplay

Baseball is played between two teams of nine players each on a baseball field, usually under the authority of one or more officials, called 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 four bases. Numbered anti-clockwise, first, second and third bases are cushions (sometimes informally referred to as bags) shaped as 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 (27.4m) called the diamond. Home base is a pentagonal rubber slab known as simply home.

The field is divided into two main sections: the infield containing the four bases is bounded by the foul line and the grass line; and the outfield which is the grassed area beyond the infield grass line, between the foul line, and bounded by a wall or fence. The area between the foul lines, including the foul lines, is fair territory, and the area outside the foul lines is foul territory.

The game is played in nine innings in which each team gets one turn to bat and try to score runs while the other pitches and defends in the field. In baseball, the defence 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. In the case of a tie, additional innings are played until one team comes out ahead. At the start of the game, all nine players of the home team play the field, while players on the visiting team come to bat one at a time.

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 to receive it. 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 side of the pitcher's rubber a 61 cm x 15 cm plate located atop the pitcher's mound during the entire pitch, so they can only take one step forward in delivering the ball. The catcher's job is to receive any ball that the batter misses or does not swing at, and, most importantly, to "call" the game by a series of hand movements that signal to the pitcher what pitch to throw and where. If the pitcher disagrees with the call, they will "shake off" the catcher by shaking their head no; they accept the sign by nodding. 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 their next turn at bat. There are many ways to get batters and baserunners out; some of the most common are catching a batted ball in the air, tag outs, force outs, and strikeouts. After the fielding team has put out three batters, that half of the inning is over and the team in the field and the team at bat switch places; there is no upper limit to the number that may bat in rotation before three outs are recorded. Going through the entire order in an inning is referred to as "batting around". It is indicative of a high scoring inning. A complete inning consists of each opposing side having a turn (three outs) on offence.

The goal of the team at bat is to score runs; a player may do so only by batting, then becoming a base runner, touching all the bases in order (via one or more plays), and finally touching home plate. To that end, the goal of each batter is to enable baserunners to score or to become a baserunner themselves. The batter attempts to hit the ball into fair territory-between the foul lines-in such a way that the defending players cannot get them or the baserunners out. In general, the pitcher attempts to prevent this by pitching the ball in such a way that the batter cannot hit it cleanly or, ideally, at all.

A baserunner who successfully touches home plate after touching all previous bases in order scores a run. In an enclosed field, a fair ball hit over the fence on the fly is normally an automatic home run, which entitles the batter and all runners to touch all the bases and score. A home run hit with all bases occupied ('bases loaded') is called a grand slam.