A baseball infield is the square area within the four 90-foot baselines "(60-foot baselines in Little League Baseball for youths 12 years old and under)". The four bases are integral parts of the infield; a ball that touches any part of a base is considered a fair ball.
Bases First base of the
Toronto Blue Jays reaches first base safely as Chris Davis of the
Baltimore Orioles attempts to scoop a bouncing ball thrown by one of the other infielders during a game in May 2017. First base is the first of the four bases that must be touched by a runner in order to score a run for the batting team. The runner may continue running past first base in a straight line without being in jeopardy of being put out, so long as they make contact with first base and make no move or attempt to advance to second base. The first baseman is the defensive player mainly responsible for the area near first base. In some youth leagues and adult recreational leagues, a "double first base" or "safety first base" is used. A double first base is rectangular (rather than square), measuring 30 by 15 inches. It is normally colored white and orange (two 15 by 15 inches squares). It is placed with the white half in fair territory and the orange half in foul territory. The white half is used by the first baseman to make plays while the orange half is used by the runner. This creates a separation between the first baseman and runner, reducing the chance of injury on plays at first base. In the
numbering system used to record defensive plays, the first baseman is assigned the number 3.
Second base of the
Minnesota Twins leaps over a sliding
Jonathan Schoop of the Baltimore Orioles attempting to turn a
double play. Second base is the second of the four bases a runner must touch in order to score a run. Second base is mainly defended by the second baseman and the
shortstop. The second baseman and shortstop ideally possess quick feet and the ability to release the ball rapidly and accurately. One player will usually cover second base while the other attempts to field the ball. Both players must communicate well to be able to make a
double play. Particular agility is required of the second baseman in double play situations, which usually force the player to throw towards first base while their momentum carries them in the opposite direction. A runner on second base is said to be in "scoring position", since there is a higher likelihood of scoring a run from second base on a single. Since second base is the farthest from home plate, it is the most commonly
stolen base in baseball. In the numbering system used to record defensive plays, the second baseman is assigned the number 4, and the shortstop 6.
Third base Third base is the third of the four bases a runner must touch in order to score a run. The third baseman is the defensive player mainly responsible for the area nearest third base. A third baseman ideally possesses quick reaction to batted balls and a strong arm to make the long throw to first base. Third base is sometimes referred to as the "hot corner" as it's common for right-handed batters to hit the ball hard to third base, making successfully fielding the ball difficult and possibly dangerous. In the numbering system used to record defensive plays, the third baseman is assigned the number 5. Like a runner on second base, a runner on third base is said to be in "scoring position", since there is a higher likelihood of scoring a run on a single or
sacrifice fly provided that the third and final out is not recorded before they can reach home plate.
Home base Home base, usually called "home plate", is the final base that a player must touch to score a run. Unlike the other bases, home plate is a
five-sided slab of white rubber that is set at ground level.
Backstop In most MLB stadiums, the
backstop is at least 60 feet behind home plate and is composed of a lower solid wall and upper netting that protects spectators behind home plate from
wild pitches,
passed balls, and
foul balls. In recreational fields, there is usually a tall chain-link fence that surrounds the infield and the players' bench for player safety.
Baselines Baselines are straight lines between two adjacent bases normally made of chalk. Physical baselines are not drawn between first and second or second and third bases; the foul lines serve to mark the baseline between home plate and first base, and between third base and home.
Running baseline Generally,
baserunners are not required to follow the baseline. A baserunner seeking to advance more than one base typically "rounds" the base, following a more circular path. However, a runner's left-right motion is constrained when the defense tries to
tag him. At the moment the defense begins the attempt, the baserunner's running baseline is established as a direct line from his current position to the base he is trying for. A runner straying more than away from this baseline to avoid a tag may be called out.
Running lane Beginning halfway between home and first base, and ending at first base, there is a second chalk line to the right of the foul line. This second line and the part of the foul line it runs parallel to, form the running lane that defines the path in which a batter-runner must run as he is advancing to first base. Rule 6.05(k) of the
Official Baseball Rules states that if a batter-runner running to first base runs outside the running lane, and "in doing so" interferes with the fielder taking the throw at first, then the batter-runner is automatically out. First base itself is not located in the running lane, but Rule 6.05 lets the batter-runner leave the running lane "by means of a step, stride or slide in the immediate vicinity of first base" to step on first base.
Playing areas near home plate (in gray) of the
Boston Red Sox stands in the left-handed hitters' batter's box at
U.S. Cellular Field against the
Chicago White Sox on July 7,
2006.
Batter's box The batter's box is the place where the
batter stands when ready to receive a
pitch from the
pitcher. It is usually drawn in
chalk on the dirt surrounding
home plate, and the insides of the boxes are watered down before each game. The chalk lines delineating the two foul lines are rarely extended through the batter's boxes. However, those lines exist conceptually for the purpose of judging a batted ball fair or foul. In addition, inside edges of the batter's boxes are often not laid-in with chalk. Similarly, though not marked, those lines continue to exist for the purpose of the rules pertaining to the batter's box and the batter's position relative thereto. There are two batter's boxes, one on each side of home plate. The batter's boxes are wide and long. The batter's boxes are centered lengthwise at the center of home plate with the inside line of each batter's box from the near edge of home plate. A
right-handed batter would stand in the batter's box on the right side of home plate from the perspective of the pitcher. A left-handed batter would stand in the batter's box to their left. A batter may only occupy one batter's box at a time and may not legally leave the batter's box after the pitcher has come set or has started their windup. Should the batter wish to leave the batter's box once the pitcher has engaged the
rubber, they must first ask the
umpire for
time-out. Time will not be granted if the pitcher has already started their pitching motion. For playing rules relating to the batter's box, see Rules 6.05 and 6.06 of the
Official Baseball Rules.
Catcher's box The catcher's box is an area of the field behind home plate which the catcher occupies to avoid committing a balk when a pitch is thrown.
Pitcher's mound pitcher
Gil Meche moves forward off the rubber as the pitch is released. In roughly the middle of the diamond, equidistant between first and third base, and a few feet closer to home plate than to second base, is a low artificial hill called the pitcher's mound. This is where the
pitcher stands when throwing the
pitch. Atop the mound is a white rubber slab, called the pitcher's plate or pitcher's rubber. It measures front-to-back and across, the front of which is exactly from the rear point of home plate. This peculiar distance was set by the rule makers in 1893, not due to a clerical or surveying error as popular myth has it, but intentionally (further details under
History). In
Major League Baseball, a regulation mound is in diameter, with the center from the rear point of home plate, on the line between home plate and
second base. The front edge of the ''pitcher's plate
or rubber'' is behind the center of the mound, making the front edge's midpoint 60 feet 6 inches from the rear point of home plate. in front of the pitcher's rubber the mound begins to slope downward. The top of the rubber is to be no higher than above home plate. From 1903 through 1968, this height limit was set at , but in reality differed from ballpark to ballpark as the height was considered too difficult to enforce. A higher mound generally favors the pitcher, and teams that emphasize pitching (such as the
Los Angeles Dodgers) will favor a slightly higher mound. With the height advantage, the pitcher gains more leverage and can put more downward velocity on the ball, making it more difficult for the batter to strike the ball squarely with the
bat. After 1968, known among baseball historians as "
the year of the pitcher", the official height of the mound was lowered from in an attempt to "increase the batting" once again. A pitcher's mound is difficult for
groundskeepers to maintain. Usually before every game it is watered down to keep the dust from spreading. On youth and amateur baseball fields, the mound may be much different from the rule book definition due to erosion and repair attempts. Even in the major leagues, each mound gains its own character, as pitchers are allowed to kick away pieces of dirt in their way, thereby sculpting the mound a bit to their preference. The pitcher may keep a
rosin bag on the rear of the mound to dry off their hands. Major League Baseball teams are also permitted
cleat cleaners on the back of the mound. This may be a flat grate-style plate, or simply a hand tool such as a piece of wood used to remove mud and dirt from cleats. These items are allowed to remain on the backside of the mound at the discretion of the
umpire, thus reducing the probability that they will affect a live play. ==Grass line==