rule of base ball

Rules and gameplay of base ball
A game is played between two teams, each composed of nine players, that take turns playing offense (batting or hitting) and defense (fielding or pitching). A pair of turns, one at bat and one in the field, by each team constitutes an inning; there are nine innings in a game. One team—customarily the visiting team—bats in the first half (or "top") of every inning; the other team—customarily the home team—bats in the second half (or "bottom") of every inning. The goal of a game is to score more points (runs) than the other team.

The players on the team at bat attempt to score runs by completing a tour of (circling) the four bases set at the corners of the square-shaped baseball diamond. A player bats at home plate and must proceed counterclockwise to first base, second base, third base, and back "home" in order to score a run. The team in the field attempts both to prevent runs from scoring and to record outs, which remove opposing players from offensive action until their turn in their team's batting order comes up again.

When three outs are recorded, the teams switch roles for the next half-inning. If the score of the game is tied after nine innings, extra innings are played to resolve the contest. Children's games are often scheduled for fewer than nine innings.
Diagram of a baseball field (the term diamond may be used to refer to the square area defined by the four bases or to the entire playing field). The dimensions given are for professional and professional-style games; children often play on smaller fields.
The game is played on a field whose primary boundaries, the foul lines, extend forward from home plate at 45-degree angles. The 90-degree area within the foul lines is referred to as fair territory; the 270-degree area outside them is foul territory. The part of the field enclosed by the bases and several yards beyond them is the infield; the area farther beyond the infield is the outfield. In the middle of the infield is a raised pitcher's mound, with a rectangular rubber plate (the rubber) at its center. The outer boundary of the outfield is typically demarcated by a raised fence, which may be of any material and height (many amateur games are played on fields without a fence). Fair territory between home plate and the outfield boundary is baseball's "field of play", though significant events can take place in foul territory, as well.
There are three basic tools of baseball: the ball, the bat, and the glove or mitt:
The baseball is about the size of an adult's fist, around 9 inches (23 centimeters) in circumference. It has a rubber or cork center, wound in yarn and covered in white cowhide, with red stitching.
The bat is a hitting tool, traditionally made of a single, solid piece of wood; other materials are now commonly used for nonprofessional games. It is a hard round stick, about 2.5 inches (6.4 centimeters) in diameter at the hitting end, tapering to a narrower handle and culminating in a knob. Bats used by adults are typically around 34 inches (86 centimeters) long, and not longer than 42 inches (106 centimeters).
The glove or mitt is a fielding tool, made of padded leather with webbing between the fingers. As an aid in catching and holding onto the ball, it takes various shapes to meet the specific needs of different fielding positions.

Protective helmets are also standard equipment for all batters.At the beginning of each half-inning, the nine players on the fielding team arrange themselves around the field. One of them, the pitcher, stands on the pitcher's mound; he will begin his pitching delivery with one foot on the rubber, pushing off it in order to gain velocity when throwing toward home plate. Another player, the catcher, squats on the far side of home plate, facing the pitcher. The rest of the team faces home plate, typically arranged as four infielders—who set up along or within a few yards outside the imaginary lines between first, second, and third base—and three outfielders. In the standard arrangement, there is a first baseman positioned several steps to the left of first base, a second baseman to the right of second base, a shortstop to the left of second base, and a third baseman to the right of third base.

The basic outfield positions are left fielder, center fielder, and right fielder. A neutral umpire sets up behind the catcher.Gameplay starts with a batter standing at home plate, holding a bat. The batter waits for the pitcher to throw a pitch (the ball) toward home plate, and attempts to hit the ball with the bat. The catcher catches pitches that the batter does not hit—as a result of either electing not to swing or failing to connect—and returns them to the pitcher. If the batter hits the ball into the field of play, he must drop the bat and begin running toward first base, at which point he is referred to as a runner. If the runner successfully reaches first base, he is said to be safe there; he has recorded a hit and is now on base. He may choose to remain at first base or attempt to advance to second base or even beyond—however far he believes he can reach safely. Any runners already on base may attempt to advance on batted balls that contact the ground (land) in fair territory, before or after the ball lands; a runner on first base must attempt to advance if a ball lands in play. If the ball is hit in the air within the foul lines over the entire outfield (and outfield fence, if there is one), it is a home run: the batter and any runners on base may all freely circle the bases, each scoring a run.

This is the most desirable result for the batter. If the ball is hit in the air and caught before it lands, the batter has flied out and any runners on base may attempt to advance only if they tag up or touch the base they were at when the play began, as or after the ball is caught. Runners may also attempt to advance to the next base while the pitcher is in the process of delivering the ball to home plate—a successful effort is a stolen base.
A pitch that is not hit into the field of play is called either a strike or a ball. A batter strikes out if he gets three strikes. He is awarded a base on balls or walk, a free advance to first base, if he is thrown four balls. (A batter may also freely advance to first base if any part of his body or uniform is struck by a pitch before he either swings at it or it contacts the ground.) Crucial to determining balls and strikes is the umpire's judgment as to whether a pitch has passed through the strike zone, a conceptual area above home plate extending from the midpoint between the batter's shoulders and belt down to the hollow of the knee.
A strike is called when one of the following happens:
The batter lets a well-pitched ball (one within the strike zone) go through to the catcher.
The batter swings at any ball (even one outside the strike zone) and misses.
The batter hits a foul ball—one that either initially lands in foul territory or initially lands within the diamond but moves into foul territory before passing first or third base. If there are already two strikes on the batter, a foul ball is not counted as a third strike; thus, a foul ball cannot result in the immediate strikeout of the batter.
A ball is called when the pitcher throws a pitch that is outside the strike zone, provided the batter has not swung at it.

A shortstop tries to tag out a runner who is sliding headfirst, attempting to reach second base.
While the team at bat is attempting to score runs, the team in the field is attempting to record outs. Among the various ways an out may be recorded, five are most common:
The strikeout: as described above, the batter is out if three strikes are recorded against him before he puts the ball into play or is awarded a free advance to first base.
The flyout: as described above, the batter is out if he hits a ball in the air and a fielder catches it, whether in fair territory or foul territory, before it lands, whether or not the batter has run.
The ground out: the batter (in this case, batter-runner) is out if he hits a ball that lands in fair territory and, before he can reach first base, a fielder retrieves it and touches first base while holding the ball or relays it to another fielder who touches first base while holding the ball.
The force out: a runner is out if he is required to attempt to advance—either because he is on first base and a batted ball lands in fair territory, or because the runner immediately behind him on the basepath is thus required to attempt to advance—but fails to reach the next base before a fielder touches the base while holding the ball. The ground out is technically a special case of the force out.
The tag out: a runner is out if he is not touching a base and a fielder touches him with the ball or a glove holding the ball.
Players put out or retired must leave the field, returning to their team's dugout or bench. A runner may be stranded on base when a third out is recorded against another player on his team. Stranded runners do not benefit the team in its next turn at bat—every half-inning begins with the bases empty of runners.
An individual player's turn batting or plate appearance is complete when he reaches base (or hits a home run), makes an out, or hits a ball that results in his team's third out, even if it is recorded against a teammate. On rare occasions, a batter may be at the plate when, without his having hit the ball, a third out is recorded against a teammate—for instance, a runner getting caught stealing (tagged out attempting to steal a base). A batter with this sort of incomplete plate appearance starts off his team's next turn batting; any balls or strikes he recorded the previous inning are erased. A runner may circle the bases only once per plate appearance and thus can score at most a single run per batting turn. Once a player has completed a plate appearance, he may not bat again until the eight other members of his team have all taken their turn at bat. The batting order is set before the game begins, and may not be altered except for substitutions. Once a player has been removed for a substitute, he may not reenter the game. Children's games often have more liberal substitution rules.
If the designated hitter (DH) rule is in effect, each team has a tenth player whose sole responsibility is to bat (and run). The DH takes the place of another player—almost invariably the pitcher—in the batting order, but does not field. Thus, even with the DH, each team still has a batting order of nine players and a fielding arrangement of nine players.