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 take only 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 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 players from the opposing team, 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" and it is indicative of a high-scoring inning. A complete inning consists of each opposing side having a turn (three outs) on offense.

The goal of the team at bat is to score more runs than the opposition; a player may do so by batting, then becoming a baserunner, touching all the bases in order (via one or more plays), and finally touching home plate. A player may also become a baserunner by being inserted as a pinch-runner. To that end, the goal of each batter is to enable baserunners to score or to become a baserunner himself. The batter attempts to hit the ball into fair territory—between the baselines—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 has successfully touched home plate without being retired (called out) after touching all previous bases scores a run. In an enclosed field, a fair ball hit over the fence on the fly is an automatic home run, which entitles the batter and all runners to touch all the bases and score. On a field with foul poles, a ball that hits a pole is also a home run. A home run hit with all bases occupied ('bases loaded') is called a grand slam.
What are the general rules of the Baseball?
Baseball is a game contested between two teams of 9 players. The defense plays the field and has the ball, and the offense can score by batting the ball and making their way around the bases. The field consists of two parts, the infield, which contains the bases, and the outfield. The bases are 90 feet apart, arranged in diamond format, and advanced counterclockwise. The pitcher's mound is in the center of the infield and is 60 feet 6 inches away from home plate (where the batter stands to try and bat the ball). At the youth level, the bases may be placed as close as 60 feet apart, and the mound may be as close as 46 feet away. The infield contains 6 of the 9 defenders, the pitcher being on the pitcher's mound, the catcher positioned behind home plate to receive the ball from the pitcher, and 4 infielders. The 1st baseman and 2nd baseman are positioned on the right side of the infield near their respective bases. The shortstop and third baseman are positioned on the left side of the infield with the shortstop shaded closer to 2nd base, in a mirrored position from the 2nd baseman. The third baseman is positioned by third base. The outfielders are the 3 remaining defensive players positioned in the large grass outfield in a left, center, and right arrangement. The pitcher must deliver the ball over the plate at the height range of the player's knees to their torso. 3 pitches at this level or swings and misses count as an out. Balls batted that don't land in play, which the lines of play extend from the point of the home plate which is a 90-degree angle count as a strike as long it strikes one or two, a batter cannot foul out for the third strike. If a pitched ball is not called a strike it is a ball, and 4 balls in an at-bat award the batter first base via what is called a walk. Other ways to make outs are if a ball is batted and the fielders catch it before it hits the ground; if the ball hits the ground the runner can be declared out of the fielders touch the base of the advancing runner with possession of the ball prior to the runners' arrival, so long as the runner is forced to advance to the base. If there is no force, the runner must be tagged out. In the event of a fly-out, any runner must re-establish possession of the bag they started at and are not allowed to advance to the next base until the fielder catches the ball. If they don't re-establish possession of their originating base they can be called out if the ball and the fielder possessing it reaches the originating base before they do. 3 outs constitute a half-inning; after each half-inning, the teams rotate from offense to defense. After each team gets 3 outs the full inning is concluded. A game is complete after 9 innings, although youth games are usually 6 or 7 innings. If the teams are tied at the end of regulation, the teams will continuously add extra innings until the tie is broken. A ball that is batted over the outfield fence is considered a homerun and the batter and all base runners can advance safely to home. If a battled ball lands in fair territory and leaves the field of play, it is considered a ground-rule double, and all runners are awarded two bases from where they started. You can substitute players from your bench into the game at any time but players are not allowed to re-enter the game once substituted, so substitutions are done sparingly and strategically. Many leagues employ the designated hitter rule, which allows for a 10th player to bat in place of the pitcher. Balls, strikes, and outs are called by umpires, of which there can be anywhere between 2 and 4.