Baseball team play
In the game of baseball, one team comes up to bat while the other team has a pitcher and plays defense on the field:
The fielding team
The fielding team has a pitcher, who stands on the mound, and a catcher, who squats behind home plate. (This pair is often called the battery.) There are also four infielders, who stand at the edge of the infield, and three outfielders, who stand in the outfield.
The pitcher must keep one foot in contact with the top or side of the pitcher's rubber during the entire pitch, so he cannot take more than one step forward in delivering the ball. Nevertheless, most major-league pitchers throw the ball at about ninety miles per hour. Pitchers must also assist fielders as necessary.
The catcher's main role is to receive the pitch if the batter does not hit it. Catchers are also responsible for defense in the area immediately surrounding home plate. Together with the pitcher and coaches, the catcher plots game strategy by suggesting different pitches and by shifting the starting positions of the other fielders.
The four infielders are the first baseman, second baseman, shortstop, and third baseman. The first and third basemen usually play near their respective bases. The second baseman and the shortstop position themselves at a roughly equal distance from second base, but play more in the gaps between the bases than the first and third baseman. As a result of this positioning, defensive skill tends to be more important for second basemen and especially shortstops. Originally, the second baseman played very close to second base, until the shortstop was developed by relocating what was previously a fourth outfielder.
The team's strongest hitter is often the first baseman. The first baseman's job consists mostly of standing with his foot on first base, waiting to receive the batted balls that the other infielders throw to him so that he can force out the batter-runner. The second baseman covers the area to the right of second base, and provides backup for the first baseman. The shortstop fills the critical gap between second and third bases, where right-handed batters generally hit ground balls. The shortstop must be versatile—he also covers second or third bases and the near part of left field (known as short left field). After the pitcher, he is usually the poorest hitter on the team. The third baseman's primary requirement is a very strong throwing arm so that he can throw the ball all the way across the infield to the first baseman.
The three outfielders are called the left fielder, the center fielder, and the right fielder; each position is named from the catcher's perspective. The center fielder has more territory to cover than the other two outfielders, so he must be very fast and agile, and must have a strong arm to throw balls in to the infield; as a result, teams tend to emphasize defense at that position. Also, the center fielder is considered the outfield leader and left- and right-fielders should cede to his direction when fielding a fly ball.
The batting team
The team at bat sends its nine players up to home plate as batters in an order called a lineup. Each team sets its batting lineup at the beginning of the game and may not change the order, except by sending in substitute players. A substitute player fills the same spot in the order as the player he replaced (however, he is not required to play the same position in the field). After the ninth player has batted, the order returns to the beginning with the first player in the lineup.
Each player's turn at the plate is a plate appearance. When the batter hits a fair ball, he must run to first base, and may continue or stop at any base unless he is put out. A successful hit where the batter stops at first base is a single; if he stops at second base, a double; at third base, a triple. If, after touching first base, the batter-runner is out while running, he is attributed a single, double, or triple according to the last base he touched before being out. A hit that allows the batter to score on the same play is a home run, whether or not the ball is hit over the fence. Runners may advance, but are not required to unless the batter displaces them.
Once the batter and any existing runners have all stopped at a base, or been put out, the next batter comes to the plate. This continues until three outs have been recorded, at which point the teams exchange sides.