How Baseball Works

By: Kevin Bonsor & Joe Martin  | 
Swing and a miss Donald Miralle / Getty Images

Baseball is a game played with a bat, ball and glove. The fundamentals of the game involve throwing the ball, hitting the ball, and catching the ball. Of course, the execution of these three tasks is more challenging than it sounds, and it is that challenge that compels baseball players to play the game.

In this article, we will explain the complex game of baseball, review some of the basic rules and the equipment used and lay out the geography of a baseball field.


Baseball Basics

Unlike most games, a running clock does not limit the length of a baseball game. The two competing teams play over a period of innings, which are subdivided into halves. Professional and college games are generally nine innings long.

­During the first half of each inning, the visiting team bats and attempts to score points, called runs, while the home team players take their respective defensive positions in the field. The defense's goal is to get the offensive team's players "out" in a variety of ways. After three outs are recorded, the teams switch -- the offensive team moves to defense, and the defensive team moves to offense. The batting team sends one player at a time to try and hit the ball.

The engine of the sport is composed of two players -- the pitcher and the batter. All of the action in a baseball game revolves around these two combatants. The pitcher stands on a raised mound of dirt, called the pitcher's mound, which is 60 feet 6 inches (18.4 meters) from home plate in Major League Baseball. The batter stands on either side of the home base, called "the plate," holding a bat and facing the pitcher.

To set the game in motion, the pitcher attempts to throw the ball past the batter into the catcher's glove or make the batter hit the ball to put it in play. As the ball is put in play, the eight fielders try to catch it or throw out the batter (more on this later) so he can't get on base and ultimately score a point (a run). The batter's goal is to put the ball in play so that the eight fielders can't catch the ball or throw it to another fielder to record an out.

The pitcher and the batter are at the center of the action.

Now that you have a basic understanding of how the game works, let's take a deeper look into the game of baseball, starting with the basic equipment.


Baseball Equipment

Former Atlanta Braves outfielder Gary Sheffield gets ready to catch a fly ball.
Photo courtesy Atlanta Braves

You need very little equipment to play a baseball game. The essential pieces are nine gloves (one for each fielder), one ball, and one bat. The batter and catcher also require some special protective gear. The following is a list of some basic baseball equipment:

  • Ball - An official baseball is manufactured through a process of wrapping yarn around a cork or rubber center and then tightly stitching a cowhide or horsehide cover over the yarn. A baseball is a sphere that is approximately 9 inches (23 cm) in circumference and weighs 5 1/4 ounces (149 g).
  • Bat - A bat is a solid piece of wood, usually ash, that is 2.75 inches (7 cm) in diameter at the thickest part, which is called the barrel, and not more than 42 inches (107 cm) in length.
  • Batting helmet - A helmet protects a baseball player if a ball accidentally hits him in the head. Some pitcher's can throw a baseball as fast as 100 miles per hour (161 kph), so a player needs to wear a helmet to prevent severe head injuries.
  • Batting glove - Although not a required piece of equipment, many batters wear gloves to protect their hands while batting. Blisters may be caused by not wearing batting gloves. Some players wear these gloves while running bases to protect their hands while sliding into bases.
  • Fielding glove - A glove may vary based on the player's position, but it is typically leather with a webbed pocket, which forms a small basket.
  • Cleats - All ball players wear a particular type of shoe called cleats, which are defined by the spikes attached to the soles. Baseball cleats have spikes near the toe of the shoe, which differentiates it from cleats in other sports.
  • Catcher's equipment - A catcher is the target for the pitcher, so the catcher must wear protective gear that covers the majority of his body. Catcher's gear includes a helmet with a faceguard that is similar to a hockey goalie's mask, a chest protector, shin guards, and a special padded glove. Some catcher's also wear devices called knee savers, which are triangular pads that attach to the players calves and rest his knees even while squatting behind the plate.
Former Atlanta Braves catcher Javy Lopez adjusts his chest protector and helmet.
Photo courtesy Atlanta Braves

With the equipment in-hand, the competitors take the field. In the next section, you will learn the basic layout of a baseball field.


Baseball Diamond

Layout of a typical baseball diamond

Like any sport, the field on which the game is played defines baseball. Once you understand the field, you can then better understand how the game works. The baseball field is unique in sports. Unlike most team sports that play on a rectangular field (e.g. basketball, football and soccer), baseball is played on a wedge-shaped field, which resembles a quarter of a circle. The field is often referred to as a diamond.

The baseball diamond is defined by two lines, called foul lines, which meet at home plate and extend outward, perpendicular to each other. These foul lines create a boundary on each side of the field between fair territory and foul territory. Everything on the outside of the foul line, including the area behind home plate, is considered foul territory. Foul territory is designated as "out of play," which means baseballs hit there don't count as a hit. However, the ball can be caught in foul territory. Foul territory also includes:


  • Team dugouts - The sheltered area on either side of the field where players stay when they aren't on the field
  • Bullpen - The area where pitchers practice before entering the game
  • Base coach's boxes - An area next to first and third base that coaches stand in to instruct the base runners
  • On-deck circles - A small circle outside the dugout where the player next in order to bat stands to practice his swing before batting
  • Seats - The seats of a typical stadium wrap around the entire field. Almost the only seats that aren't in foul territory are those beyond the outfield wall between the foul lines.

Inside the foul lines, or fair territory, is where most of a baseball game's action takes place. Fair territory is subdivided into the infield and the outfield. On most fields, the dividing line between the two is where the grass of the outfield meets the dirt of the infield. The parts of the infield include:

  • Bases - The Bases are the four stations (first base, second base, third base, and home plate) that players must run to after hitting the ball into play. Each base is 90 feet (27 m) apart in a Major League Baseball game. A run is scored when a player reaches home plate.
  • Base paths - The base path is the line between each base that the player must run along to reach a base. A player can be called out for running outside of the path.
  • Pitcher's mound - The pitcher's mound is the raised mound of dirt in the middle of the infield on which the pitcher stands.
  • Batter's box - The batter's box is marked off by two small rectangles flanking home plate. The batter must stand within the borders of the box to hit.

Now that you are familiar with the geography of a baseball field, let's look at the players and their positions.

Baseball Defense

Defensive positions

A baseball game is played between two teams -- the home team and visiting team. Often, the name of the visiting team's city is displayed across the front of the players' jerseys. Each team has at least nine players, and each player occupies a designated spot on the field. Most professional teams have many more than nine players, which allows for substitutions.

During an inning, teams take turns batting. While one team is batting, the other team puts its players in specific areas of the field in order to prevent the other team from getting hits and scoring runs. Each player of the batting team takes his turn going to home plate, standing in the batter's box, and trying to hit the ball that the pitcher throws toward him. He does so by swinging the bat as the ball nears home plate.


In all, there are nine positions on the defensive side:

  1. Pitcher - Stands on the pitcher's mound and throws the ball to the catcher in attempt to make the batter either swing and miss or else put the ball in play so that it can be caught by a defensive player (in which case the batter is "out")
  2. Catcher - Squats behind home plate and catches the pitcher's throws; also throws to bases to throw out player's trying to steal those bases, as well as fields the area around home plate
  3. First baseman - Fields the area near first base
  4. Second baseman - Fields the area between first and second base
  5. Third baseman - Fields the area near third base
  6. Shortstop - Fields the area between second and third base
  7. Left field - Fields the portion of the outfield that's on the left side of the batter when he faces the field
  8. Center field - Fields the middle portion of the outfield
  9. Right field - Fields the portion of the outfield that is on the right side of the batter when he faces the field
Former Atlanta Braves second baseman Marcus Giles leaps over an opposing player to complete a double play.
Photo courtesy Atlanta Braves

All of the fielders work together to prevent the batters and base runners of the other team from getting hits and scoring runs. An out is recorded when a fielder catches a ball, tags a base runner with a ball, or grabs the ball and steps on the base a runner is trying to reach before the runner reaches it. Outs are also recorded when a hitter strikes out (see the next section). Once three outs are recorded, a half-inning is finished. In the next section, we will look at the offensive side of the game.

Baseball Offense

Braves outfielder Andruw Jones rounds third base.
Photo courtesy Atlanta Braves

On the offensive side of the game, there are two types of players -- the hitter and the base runner. Once the hitter makes contact with the ball and gets a hit, he becomes a base runner and must safely reach each base in succession. The ultimate goal of each offensive player is to make his way around the bases and cross home plate, thereby scoring a run.

When a hitter is at the plate, he is considered to be at bat. During an at bat, the pitcher of the opposing team throws the ball to the catcher, and the hitter tries to hit the ball with the bat before it reaches the catcher. Each throw is called a pitch. A pitch can be either a ball or a strike. (The umpire is the judge of whether a pitch is a ball or a strike.)


A ball is a pitch that is out of the strike zone, which is an imaginary rectangular box that typically runs the width of the plate and from the hitter's chest to his knees. A strike is a ball that goes through the strike zone and is not hit by the hitter. A strike can be a ball outside of the strike zone if the hitter swings and misses. If a player hits a ball that goes into foul territory and is not caught by a fielder before it touches the ground, it is also counted as a strike -- except when the batter already has two strikes. A batter with two strikes can hit the ball into foul territory indefinitely without striking out. However, a ball caught in foul territory is scored an out.

During an at bat, a hitter may do one of several actions, including:

  • Walk - When the pitcher throws four balls before throwing three strikes, the hitter gets a free base.
  • Hit by pitch - A hitter that is struck with a pitch is awarded first base.
  • Single - The hitter hits the ball into play far enough to get to first base.
  • Double - The hitter hits the ball into play far enough to get to second base.
  • Triple - The hitter hits the ball into play far enough to get to third base.
  • Home run - The hitter hits the ball over the outfield wall between the foul poles and is awarded a free trip around the bases, or the hitter hits the ball far enough that he or she has time to run all the bases. The hitter must run around the bases and touch home plate for the home run to count.
  • Fielder's choice - A hitter makes contact with the ball, but only reaches base because a fielder chose to throw out another runner.
  • Error - A hitter makes contact with the ball and only reaches base because a fielder misplays the ball.

A runner must go around the bases in order, starting with first base. He then goes to second, third, and finally home. A base runner can advance in one of several ways. He can be advanced by another player's hit or by a hitter being walked, or he can steal a base. To steal a base, the runner starts running from one base to another before the at-bat player gets a hit or a walk, and makes it to the base without getting tagged out. If a runner veers outside of the base path, the umpire calls him out. The umpire decides how far outside the base path is too far.

At the end of all the scheduled innings, the team that has scored the most runs is declared the winner. If the home team is ahead after the top of that inning, the home team wins the game and does not have to complete the inning. However, if the teams are tied after nine innings, they continue to play until one team has more runs than the other. Keep in mind that the home team always has the chance to bat last.


Special Rules

Now that you know the basics, you can see how on the face of it baseball is a simple game. Of course, while it is simple in concept, it can also become extremely complex based on different rules that have been put in place over the 140 years the game has been played. Here are a few of those:

  • Ground rule double - As has already been discussed, if a ball is hit over the outfield fence in fair territory, it is a home run. However, if a ball bounces over the fence, it is an automatic double.
  • The foul pole - Because balls traveling in the air over the outfield fence can never hit the ground in fair territory, poles are set up on the foul line in left and right fields. These have always been known as foul poles. However, a ball hitting one of these poles is considered a fair ball, and therefore a home run.
  • Tagging up - If there is a runner on base, he must not advance from his base until a hit ball hits the ground. The exception to that is if the ball is caught by a fielder, the runner can advance once the ball is caught, but only after touching the base he was at when the ball was hit. This is called tagging up, and the fielder can attempt to record another out by tagging (or assisting his teammate in tagging) the runner before he advances to the next base. This can often result in one of the more exciting plays in a game, a close play at home plate.
  • Dropped third strike - As discussed earlier, a batter is out if he has three strikes during an at bat. However, if the catcher drops or otherwise does not catch the pitched third strike, the batter can still be awarded first base if he can reach it before the catcher is able to either tag him or throw the ball to first base before he reaches it. While this is still a strikeout, it does not count as one of the three outs for that half inning. This odd quirk presents the pitcher with a strange opportunity, the ability to record four strikeouts in one inning.
  • Infield fly rule - If there are two or more runners on base with fewer than two outs, a fly ball that is not hit far enough into the field is an automatic out as a result of the infield fly rule. Since when a ball is still in the air, runners must remain on base, this rule prevents a fielder from purposely letting the ball drop and then recording an easy double play, since neither of the runners would have moved yet.
  • Balk - Similar to the infield fly rule, this rule is designed to prevent the defensive team, in this case the pitcher, from misleading base runners. Because runners who are trying to steal bases must do so based on timing the pitcher's throwing motion, pitchers are prohibited from trying to deceive the runner by starting their motion and then stopping. Once the motion has begun, the pitcher must deliver the pitch to the plate. If a balk is called as a result of the pitcher making what is ruled by the umpire a deceptive move, the runner or runners are all awarded one base.


The Major League Baseball Season

Former Atlanta Braves pitcher Russ Ortiz
Photo courtesy Atlanta Braves

At the highest level of baseball, the Major Leagues, the baseball season can last from February until late October. It's generally broken down into three parts: pre-season, regular season, and post-season.

The pre-season, or spring training, is really not much more than practice. The players report to a warm climate (Florida or Arizona) to get in shape for the coming season. Since pitchers have the bulk of the duty during a game, they also need a little longer to prepare. And since a pitcher is not much good without someone to catch the ball, pitchers and catchers report to spring training a week or so before the rest of the players do. In early February, you'll hear die-hard baseball fans counting down the days until "pitchers and catchers." To them, this is as much an indication of the end of winter as birds flying north.


Major League Baseball is broken up into two leagues, the American League and the National League. Each of the leagues is also broken into three divisions: East, Central and West.

The regular season is a grueling 162 games, played from early April until the last week in September. Over that time, teams play a large number of games within their division, virtually all within their own league, although in recent years they have also played a handful of games against the opposite league. These 162 games are played with the intention of determining the best team in each division, for purposes of playing in the post season. At the end of the season, the teams with the best records in each of the six divisions qualify for the playoffs. In addition, one additional team from each league qualifies as a wild card. The team with the best record that has not won a division is declared the wild card in each league.

The Post Season

Former Atlanta Braves outfielder Gary Sheffield at bat
Photo courtesy Atlanta Braves

The post season generally begins in the first week in October with the Division Championship Series -- four separate series of games, two in each league. The division champion with the best record usually plays the wild card from its own league in a best-of-five series, and the remaining two division champions play each other in a similar five game series. All four of these series are structured so that the team with the better regular season record has home field advantage, essentially meaning that either two or three games -- the first two and, if necessary, the final game -- are played in that team's home stadium. In each of those four series, the first team to win three games advances to the next round of the playoffs, called the League Championship Series.

Once all the position players have arrived, spring training is composed of weeks of practice sessions, exhibition games and other scrimmages. It's during that time that the coaching staff makes a final determination of which players should go with the team to the regular season of the Major Leagues, or be assigned to the various levels of the Minor Leagues (see How Minor League Baseball Teams Work).


Each League Championship Series is a best-of-seven series. The home field advantage goes once again to the team with the best regular season record, which means in this case that that team will host the first two games, as well as the last two games, if they are necessary, with the middle three games being played at the opponent's stadium. The first team in each league to win four games is declared League Champion, and advances to the World Series for the chance to become World Champion.

Called the Fall Classic, the World Series pits the two league champions against each other in a best-of-seven-games series, structured much like the Championship Series in the round before. Home field is not determined based on record, but on the result of the All-Star Game, which is played in mid-July. Whichever league's all-star team wins the All-Star Game becomes the host team for the World Series. This is a very recent change, used for the first time in 2003. Prior to 2003, the home field was determined simply on a rotating basis -- one year the American League would host, the following year the National League, and so on.

The other major difference between the World Series and the other games is the application of rules. The two leagues have a few subtle differences and one major difference: the designated hitter. The American League uses the designated hitter and the National League does not, meaning that National League teams have to use their pitchers to hit. In the World Series, the designated hitter is used by both teams when they're playing in the American League park, and by neither team when they're in the National League park.

As in the Championship Series, the winning team is the first to win four games. That team is declared World Champion.

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