Baseball is a bat-and-ball sport played on a field by two teams against each other. In baseball, a player on one team throws a small round ball at a player on the other team, who tries to hit it with a bat. Then the player who hits the ball has to run around the field. Players get runs by running around in a full circle around three points on the ground called bases, to back where they started, which is called home plate. They have to do this without getting caught by the players on the other team.

Baseball started in the United States in the 1700s and 1800s. Many people in North America, South America, and East Asia play baseball, but the sport is most known in the United States and Japan. In the U.S., baseball is called the national pastime, because so many people in the United States used to spend a lot of time playing or watching baseball games. Today, though, most Americans follow football more than baseball, especially when it comes time for the Super Bowl.

How baseball is played 

A game of baseball is played by two teams on a baseball field. Each team has 9 players. There are also 4 umpires. There is one for where young players play. Umpires watch everything carefully to decide what happened, make calls about a play, and make sure everyone follows the rules.

On a baseball field, there are four bases. The bases form a diamond that goes around the field to the right from the starting base. The starting base is called home plate. Home plate is a pentagon, which is a shape that has five sides. First base is on the right side of the field, second base is at the top of the infield, third base is on the left side of the field, and home plate is at the back of the field, where the catcher plays.

The game is played in innings. Professional baseball games have 9 innings. In an inning, each team has one turn to bat and try to score runs, adding one point. When one team hits the ball, the other team defends and tries to get three players on the other team out. The team that is playing defense always has the ball. This is different from other team sports. When the team on defense gets three players out, it is their turn to try and score runs. Then the team that was batting starts playing defense, and the team that was playing defense starts batting. After nine innings, the team that has the most runs is the winner. If the teams have the same number of runs, they play more innings until one team wins. At the start of the game, the home team pitches, while players on the visiting team bat. Only one player can bat at a time.

The baseball field, or diamond, has two main parts, the infield and the outfield. The infield is where the four bases are. The outfield is beyond the bases, from the view of home plate. The lines from home plate to first base and home plate to third base are the foul lines, and the ground outside of these lines is called foul territory. A ball that is hit with a bat and flies between the foul lines is a fair ball, and the batter and runners can try and run around the bases and score. A ball that is outside the foul lines is a foul ball. If the ball hits the ground in  the foul area  rather than being caught in the air, the batter continues to bat, and any runners must return to the base that they were on before the ball was hit. If the batter has fewer than two strikes, a foul ball counts as a strike. If the batter already has two strikes, and the foul ball is not caught in the air, then the batter continues to hit. If a ball is caught by a fielder in fair or foul ground, the batter is out.

The most important part of the game is between the pitcher and the batter. The pitcher throws, or pitches, the ball towards home plate. The pitcher normally throws the ball close enough for the batter to hit it. If the pitcher throws the ball in the strike zone, which is the area  over home plate and between the hitter's knee and chest, the pitch is a "strike", unless the batter hits the ball. The pitch is always a strike, regardless of where it is, if the batter swings the bat and misses, so the batter must have good aim with the bat. Three strikes are a "strikeout", and this is one way to make an "out". A pitch that the batter does not swing at, and which is not called a strike, is a "ball." On the fourth "ball" thrown by a pitcher, the batter "walks" to first base, so it is important to pitch well.

The catcher for the pitcher's team waits behind the batter, and catches any ball that the batter does not hit. The catcher uses signals to tell the pitcher where to throw the ball. If the pitcher does not like what the catcher says, he will shake his head, which signals "no". If he agrees with what the catcher has signaled, he will nod his head, which signals "yes".

There are many ways to get batters out, and runners can also be gotten out. Some common ways to get batters out are catching a batted ball in the air, whether in fair or foul territory, throwing the ball to the defensive player at first base (an out if it gets there before the batter), and a strikeout. A runner can be put out by tagging the runner while the runner is not on a base, and by "forcing him out" (when a base is touched before a player can get there, with no base for the runner to go back to). When the fielding team has put out three of the batting team's players, the half-inning is over and the team in the field and the team at bat switch places.

The batting team wants to get runs. In order to get a run, a player must bat, then become a base runner, touch all the bases in order, and then touch home plate without being called out. So first, the batter wants to make other players get to home plate, or to run the bases himself. Runners can not pass each other while running the bases.

A base runner who touches home plate after touching all previous bases in order, and without getting out, scores a run. If the batter hits the ball over the fence (between the foul lines) without touching the ground, it is a home run. The batter, and any base-runners, are allowed to advance to the home plate and score a run. The fielding team can do nothing to stop them.

Fielding team 
The team on the field tries not to let the team who's batting get any runs. The fielding team has a pitcher and a catcher. The remaining seven fielders can stand anywhere in the field. However, there are usually four people that stand around the infield close to the bases and three outfielders who stand around the outfield.

The four infielders are the first baseman, second baseman, shortstop, and third baseman. The first baseman and third baseman stand close to first base and third base. The second baseman and the shortstop stand on either side of second base.

The first baseman's job is to make force plays at first base. In a force play, another infielder catches a ball that has touched the ground, and throws it to the first baseman. The first baseman must then touch the batter or the base with the ball before the batter can touch first base. Then the batter is out. First basemen need to have quick feet, stretch well, be quick and know how to catch wild throws. First base is one of the most important positions as a significant number of plays happen there.

The second baseman's job is to cover the area to the right of second base and to back the first baseman up. The shortstop's job is to cover the area between second and third bases. This is where right-handed batters usually hit ground balls. The shortstop also covers second or third base and the near part of left field. The shortstop is usually the best fielder on the team. The third baseman needs to have a strong throwing arm. This is because many times the batter will hit a ball toward third base. The third baseman must throw the ball very quickly to the first baseman, to get the runner out. Because the balls that go to third base are usually hit very hard, the third baseman must also be very quick.

The three outfielders are called the left fielder, the center fielder, and the right fielder, because they stand in left field, center field and right field. Left field and right field are on the left and right sides, if you look out from home plate. Center field is straight ahead from home plate. Center field is very big, so the center fielder is usually the fastest.

The team can decide where to put the infielders and outfielders. Players often stand at slightly different places on the field between some plays. These changes are called "shifts". The fielders may shift at any time. Players can shift for many reasons. One of the more popular ones is the defensive shift, where players move in the infield. They do this because they know that some batters can only hit a ball a certain direction. It can also be easier to make a double play when fielders are moved a certain way.

Pitching 

Teams can change pitchers during a game. Teams change their pitchers often because it is hard for a pitcher to throw a full game of nine innings. A pitcher can sometimes throw a no-hitter where no one on the opposite team gets an earned hit. A team can use as many pitchers as it wants to, but it is rare to use more than eight in a game. The ways that a pitcher throws the ball are called pitches. Many professional pitchers use two or more different pitches. Pitchers change which  pitch they throw so that the batter will be tricked and not know what pitch to expect. This makes it more difficult for the batter to hit the ball. Pitchers can make the ball move differently: faster or slower, closer or farther from the batter, higher or lower. There are also many types of pitches, such as the slurve, curve, slider, splitter, sinker, screw, 2-seam cut, 2-seam screw, knuckle, knuckle curve, change-up, circle change-up, palm ball, and others.

When throwing the ball, the pitcher must touch the pitchers mound with his foot. The pitcher's rubber is on top of the mound. The pitcher cannot take more than one step forward when he throws the ball. That makes the pitcher throw the ball slower. Many major-league pitchers can throw the ball up to 100 miles per hour (145 km/h). Throwing a baseball that fast can be bad for the body. Pitchers can end up with a lot of injuries. Doctors often will perform Tommy John surgery on a pitcher with an elbow injury. The operation is named after Tommy John, the first pitcher to have the surgery. Today, pitchers are able to recover from their injuries much more often than before Tommy John surgery.

The batting team 
The batting team wants to get runs. The batting team sends its players up to home plate in a special order. This order is called the lineup. Each team chooses its lineup at the start of the game. After the game starts, the team cannot change the order. But the team can use a player who was not on the lineup. The new player has to change with an original player. The new player's name is written in the lineup where the original player's name was. After the ninth player has batted, the first player in the lineup starts again. If a runner comes to home plate, he scores a run. Then he is not a base runner. After scoring a run, the player must leave the field until it is his turn again. So a player can only score one run for each time he bats.

Since people began to have more free time, baseball has become the national pastime of America. About 12 million people play baseball in the United States.

Baseball terms

The field 
See the image above for a diagram of the playing field.
 Base: Four points on the field the players must run to. The player starts at Home plate and must go to each of the other bases in order and return to Home plate to score a run. The other bases are named First base, Second base and Third base. Home plate is a piece of hard rubber and the other bases are made of cloth. In professional baseball, the bases are 90 feet from each other. The bases on the field are in the shape of a diamond.
 Baseline: the line between each of the bases in order. For example, from home plate to first base, from first base to second base, and so on.
 Base path: The area along the baseline where the players run from base to base.
 Ball: A pitch that was thrown outside the strike zone and that the batter did not swing at.
 Strike: A pitch that was thrown inside the strike zone and that the batter did not swing at, a pitch that the batter swung at and missed, or a ball that the batter hit into foul territory.
 Dugout: the place where the players and coaches who are not on the field sit.
 Bullpen: the place where the pitchers watch the game and warm up before they start playing or when they are not playing.
 Outfield: where three players play, typically where the best arm, the fastest and the second best arm play

The Game
 Grounder: A ball that bounces and rolls on the ground after being hit.
 Pop Fly: A ball that goes high in the air after being hit. It can be caught for an out or it can fall for a hit
 Double Play: When the defense gets two outs on one play. Often happens when a ground ball is hit to an infielder with a runner on base.
 Bunt: when the batter holds his bat out to try and hit the ball rather than swinging it. A bunted ball does not go far usually. Pitchers often bunt because they are not as good at hitting. A bunt is also often used when trying to advance another runner already on one of the bases. This is called a "sacrifice" or "sacrifice bunt."
 Hit: When the batter hits the ball (thrown by the pitcher) in fair territory. 
 Home Run: When the batter hits the ball outside the baseball field, he (and any runners on base) gets to run all of the bases and scores at home plate.

Related pages
Major League Baseball
Comparison of baseball and cricket

References

Further reading 
 Dickson, Paul. The Dickson Baseball Dictionary, 3d ed. (W. W. Norton, 2009). 
 Fitts, Robert K. Remembering Japanese Baseball: An Oral History of the Game (Southern Illinois University Press, 2005). 
 Gillette, Gary, and Palmer. Pete (eds.). The ESPN Baseball Encyclopedia, 5th ed. (Sterling, 2008). 
 Peterson, Robert. Only the Ball was White: A History of Legendary Black Players and All-Black Professional Teams (Oxford University Press, 1992 [1970]). 
 Reaves, Joseph A. Taking in a Game: A History of Baseball in Asia (Bison, 2004). 
 Ward, Geoffrey C., and Ken Burns. Baseball: An Illustrated History (Alfred A. Knopf, 1996).

Other websites 
 World Baseball Softball Confederation
 "Baseball". Encyclopædia Britannica Online.
 Baseball Prospectus
 Society for American Baseball Research
 The Rules of Baseball
 Baseball Heritage Museum at League Park in Cleveland, Ohio