Baseball is won by scoring more runs than the opposition. Each team takes turns batting and fielding, with three outs ending a team’s turn at bat. A Major League Baseball game normally lasts nine innings, and the team with the most runs at the end wins.
This guide follows MLB’s 2026 Official Baseball Rules and current Major League competition procedures.
The rules were checked up to 1 August 2026. Other baseball competitions may publish their own variations.
For news, analysis and coverage throughout the season, visit the World in Sport MLB section.
How Does Baseball Work?
Two teams take turns playing offence and defence. The batting team tries to move runners around four bases and score at home plate. The fielding team tries to prevent runs by retiring three offensive players.
A conventional defensive alignment consists of a pitcher, catcher, four infielders, and three outfielders. However, fielders may adjust their positions within MLB’s defensive-positioning restrictions.
The bases form a diamond. First, second and third base are separated by 27.43 metres (90 feet), while the pitching rubber is 18.44 metres (60 feet 6 inches) from the rear point of home plate. MLB’s first, second and third-base bags measure 45.72 centimetres (18 inches) square.
The visiting team bats first in the top half of each inning. The home team bats during the bottom half. Once the batting team records three outs, the teams exchange roles.
How Do Innings Work?
An inning contains two halves:
The visiting team bats in the top half.
The home team bats in the bottom half.
Each team continues batting until the defence records three outs. There is no set number of batters in an inning. A side could be retired after only three batters, or it could continue scoring and sending players to the plate until the defence finally makes the third out.
A regulation MLB game consists of nine innings unless it is extended because the score is level. Shortened because the home team is already ahead after the top of the ninth, or stopped under the rules governing called and suspended games.
The home team does not bat in the bottom of the ninth when it is already leading. The visiting team has completed its final opportunity to score, so the game ends after the third out in the top half.
What Is an Out in Baseball?
An out removes a batter or runner from the current half-inning. Three legal outs retire the side and send the opposing team to bat.
Common outs include:
A batter receiving three strikes.
A fielder catching a fair or foul fly ball before it touches the ground.
A fielder touching first base with the ball before the batter-runner arrives.
A runner being tagged while not touching a base.
A force out at the base a runner must reach.
A runner failing to touch a base and being retired on appeal.
A batter or runner committing interference.
MLB’s rulebook contains several less common ways to make an out, including the infield fly rule, batting out of order and deliberately interfering with a defensive play.
How Are Runs Scored?
A run scores when an offensive player legally touches first, second and third base before reaching home plate. The bases must be touched in that order.
The runner must normally reach home before the third out. However, timing matters when the third out is a tag rather than a force play.
For example, imagine a runner on third base and a runner on first with two outs. The batter hits the ball into the outfield. The runner from third crosses home before the runner from first is tagged for the third out. The run can count because the final out was not a force out.
A run does not count when the third out is:
A force out.
Made against the batter-runner before that player reaches first base.
Made on appeal against a preceding runner whose failure to touch a base affects the scoring play.
These exceptions explain why a runner crossing home plate does not always add a run to the scoreboard.
| Situation | Immediate result | Important detail |
|---|---|---|
| Four balls | Batter is awarded first base | Forced runners advance when necessary |
| Three strikes | Batter is normally out | An uncaught third strike can allow the batter to run in specific situations |
| Caught fly ball | Batter is out | Runners must retouch their bases before attempting to advance |
| Fair ball not caught | Batter becomes a runner | The defence must record an out or stop the runners advancing |
| Home run over the boundary | Batter and eligible runners may score | Each runner must legally touch every required base |
How Do Balls and Strikes Work?
Every plate appearance begins with a count of no balls and no strikes.
A strike is recorded when the batter swings and misses, does not swing at a pitch that passes through the strike zone, or hits certain foul balls. Three strikes usually retire the batter.
A ball is normally called when a pitch passes outside the strike zone, and the batter does not swing. Four balls give the batter a base on balls, commonly called a walk, and the batter is entitled to first base.
The strike zone is judged over home plate. In 2026, the home-plate umpire continues to make the initial ball-or-strike decision, although eligible players may challenge that call through MLB’s Automated Ball-Strike system.
Do Foul Balls Count as Strikes?
A foul ball normally counts as a strike when the batter has fewer than two strikes.
Once the count reaches two strikes, an ordinary foul ball does not create a third strike. The batter remains at the plate, and the pitch is repeated as part of the same plate appearance.
There are important exceptions. A foul bunt with two strikes results in strike three and an out. A foul tip that travels sharply into the catcher’s hand or glove and is legally caught also counts as a strike, including a third strike.
What Is the Difference Between Fair and Foul?
A fair ball is a legally batted ball that settles or travels through fair territory under the definitions in the rulebook. The foul lines and foul poles form part of fair territory.
A fair ball remains in play unless it becomes dead under another rule. The batter becomes a runner and may attempt to reach as many bases as the play allows.
A foul ball is generally dead once it touches the ground or another object in foul territory. Runners return to their previous bases, although a foul fly caught before touching the ground records an out and may allow runners to advance after retouching their bases.
A fair ball hit over the outfield boundary in flight is normally a home run. A fair ball that bounces over or becomes lodged beyond the boundary commonly results in a two-base award.
Force Outs and Tag Outs
A force play occurs when a runner must leave a base because the batter has become a runner and the following bases are occupied.
For example, with a runner on first, a fair ground ball forces that runner towards second because the batter is entitled to attempt first base. The defence can retire the original runner by controlling the ball and touching second base before the runner arrives.
A tag out is different. When no force exists, a fielder must touch the runner with the ball, or with the glove or hand holding the ball, while the runner is off a base.
The distinction is important when deciding whether a run scores before the third out. Runs cannot score on a third-out force play, but they may score before a third-out tag in the right circumstances.
Can a Batter Run After Striking Out?
Sometimes.
When the catcher does not legally catch the third strike, the batter may attempt to reach first base if:
First base is unoccupied; or
There are already two outs, whether first base is occupied or not.
The defence must then tag the batter-runner or make the out at first. When first base is occupied with fewer than two outs, the batter is out even if the catcher does not catch strike three.
This rule prevents the defence from creating an easy double or triple play by deliberately failing to catch a third strike when first base is occupied.
How Does Base Running Work?
Runners must touch the bases in order. They may advance when the batter puts the ball in play, on a walk that forces them forward. Or following an error on a wild pitch or passed ball, during a stolen-base attempt or when the rules award one or more bases.
A runner may leave a base while the ball is live, but does so at the risk of being put out. This makes stolen bases possible. The pitcher or catcher can try to retire the runner with a pick-off throw.
When a fly ball is caught, runners must retouch, or tag up at, the base they occupied when the pitch was delivered before attempting to advance. A defence can appeal when a runner leaves too early or misses a base.
What Happens when the Score Is Level?
When an MLB game is tied after nine innings, it continues into extra innings.
During regular-season games, each half-inning from the tenth onwards begins with an automatic runner on second base. The runner is normally the player in the batting order immediately before the batter due to lead off, although a legal substitute may be used. An automatic runner who scores is not charged to the pitcher as an earned run.
The automatic-runner rule does not apply during the MLB postseason. Postseason extra innings begin with the bases empty and continue under the traditional format.
The game ends when the visiting team completes an extra inning with a lead. And then records three outs against the home team, or when the home team scores the winning run in the bottom half of the inning.
A home-team winner in the bottom of the ninth or extra innings is known as a walk-off. The game normally ends as soon as the winning run scores. If the final batter hits an out-of-the-park home run, the batter and all runners are allowed to complete their trips around the bases.
MLB Pitch-Timer Rules
MLB uses a pitch timer to control delays rather than to set an overall limit on the length of a game.
Pitchers must begin their delivery before the timer expires. The limit is 15 seconds with the bases empty and 18 seconds with at least one runner on base. A violation by the pitcher produces an automatic ball.
Batters must be in the box and alert to the pitcher with eight seconds remaining. A batter who fails to meet that requirement receives an automatic strike. There is also a 30-second timer between batters.
Pitchers are permitted two disengagements during a plate appearance. A disengagement includes stepping off the pitching rubber or attempting a pick-off.
A third unsuccessful pick-off attempt results in the runner being awarded the next base. The disengagement count resets when a runner advances during the plate appearance.
For more background on the introduction of the timer, larger bases and positioning restrictions, read World in Sport’s analysis of MLB’s 2023 rule changes.
The current timer with runners are now 18 seconds, down from the original 20-second limit.
How Does MLB Restrict Defensive Shifts?
MLB requires at least four fielders, excluding the pitcher and catcher, to have both feet within the infield boundary when the pitcher begins the delivery.
At the moment of release, at least two infielders must be positioned entirely on each side of second base. The two infielders assigned to each side cannot simply exchange sides during the inning unless a permitted substitution or positional change allows it.
When a shift violation occurs, the batting team may accept the outcome of the play. Under the current penalty, the batter may instead be awarded first base if the fielder who violated the rule is the first to touch the batted ball with other runners advancing as required.
How Does the ABS Challenge System Work?
MLB introduced its Automated Ball-Strike Challenge System for Spring Training, regular-season and postseason games in 2026. Human umpires continue to call every pitch initially.
Only the batter, pitcher or catcher involved in the pitch can challenge the call. The player must challenge immediately by tapping a hat or helmet and verbally requesting the review. Managers, coaches and other players cannot initiate the process or provide assistance.
Each team begins with two ABS challenges and keeps a challenge when the call is overturned. A team entering an extra inning without a remaining challenge receives one for that inning.
The automated strike zone is a two-dimensional rectangle centred on home plate. It is 43.18 centimetres (17 inches) wide, with its upper and lower limits calculated from the batter’s measured height. If any part of the ball touches any part of the automated zone, the reviewed pitch is a strike.
Full details are available in MLB’s official ABS Challenge System announcement.
Umpires, Replay and the Official Scorer
The home-plate umpire controls the game, calls balls and strikes and rules on plays around home plate. Base umpires make safe-or-out decisions, judge catches, watch for missed bases and apply other rules within their responsibilities.
Certain decisions can be reviewed through MLB’s replay system. This is separate from an ABS ball-strike challenge.
A manager begins most games with one replay challenge and receives two during postseason and All-Star games. A successful challenge is retained. Replay officials in New York can overturn the ruling, confirm it or allow it to stand when the evidence is inconclusive.
Reviewable decisions include many tag and force plays, boundary calls, selected fair-or-foul rulings, home runs, hit-by-pitch decisions and whether a runner touched a base. Balls and strikes are not reviewed through the standard manager-challenge system.
The official scorer records hits, errors, runs, runs batted in, pitcher decisions and other statistical outcomes. The scorer does not replace the umpire or reverse an on-field safe-or-out decision.
Substitutions and the Designated Hitter
A team may make a substitution while the ball is dead. A substitute takes the replaced player’s position in the batting order.
Once a player has been removed from an MLB game, that player cannot return. This differs from some baseball formats that permit limited re-entry.
A relief pitcher must normally face at least three consecutive batters or remain until the end of the half-inning. Injury or illness can allow an earlier change when the umpire-in-chief accepts that the pitcher cannot continue.
MLB uses a designated hitter, or DH, who bats instead of the pitcher but does not normally play a defensive position. A starting pitcher who is also named as the DH can remain in the game as the hitter after being replaced on the mound. Or continue pitching after being removed as the DH.
What Happens when Weather Stops a Game?
The umpire-in-chief or MLB’s Commissioner’s Office can postpone. Suspend or call a game because of weather—unsafe field conditions, lighting problems, emergencies or other circumstances that prevent safe play.
A game reaches regulation status once five innings have been completed, or after the home team has taken the lead through the required number of completed or partial half-innings.
However, reaching the five-inning threshold does not mean every interrupted game immediately ends with a result. A tied game, or one stopped after the visiting team has taken the lead during an incomplete inning without the home team replying, is normally suspended and resumed later.
A game stopped before becoming a regulation game is also scheduled to resume rather than being replayed from the beginning.
Do All Baseball Competitions Use the Same Rules?
No. This article explains current MLB rules.
Other recognised competitions may adopt specific tournament modifications. The World Baseball Classic, for example, uses early-termination rules for large leads during its first round, while maintaining separate provisions for extra innings, pitching use and tournament progression.
Fans should therefore check the regulations of the competition they are watching rather than assuming that every professional, international, collegiate or youth game follows MLB procedures.
More explainers covering scoring systems, competition formats and sporting regulations are available in the World in Sport sports guides section.
Frequently Asked Questions
How Many Innings Are Played in Baseball?
An MLB game normally lasts nine innings. It can continue into extra innings when the score is level, or end without a bottom of the ninth when the home team is already ahead.
How Many Outs Does Each Team Receive?
Each team receives three outs during every half-inning; in a normal nine-inning game, that gives each team up to 27 outs. The home team may require fewer when it is leading after the top of the ninth.
Does Every Runner Crossing Home Plate Score?
No. The runner must touch the bases legally. And the run may be called off when the third out is on a force play. The batter-runner is retired before reaching first or a preceding runner is retired on a relevant appeal.
Is a Foul Ball Always a Strike?
A foul normally counts as a strike only when the batter has fewer than two strikes. An ordinary foul with two strikes does not end the plate appearance, although a foul bunt with two strikes results in an out.
Can a baseball game end as a draw?
A tied MLB game normally continues into extra innings until a winner is decided. The rulebook allows an exceptional suspended regulation game to be recorded as a tie if it cannot be resumed or completed under the applicable scheduling procedures.
