The object of baseball is simple to state and hard to master: score more runs than the opponent before the game ends. A run is recorded when a batter becomes a runner and advances safely around first, second, and third base to touch home plate. The team in the field prevents runs by recording outs. Each team bats until it makes three outs, completing a half-inning; a full inning has a top half and a bottom half. Regulation games last nine innings, and the home team, batting last, always knows exactly what it needs.
Every play begins with a pitch. The pitcher, working from a rubber atop a raised mound 60 feet 6 inches from home plate, throws toward the catcher through the strike zone while the batter decides whether to swing. Contact sends the ball into fair or foul territory, triggering a chase in which fielders try to catch it in the air or throw it to a base ahead of the runner. Balls, strikes, outs, and baserunners form the core state of the game, and managers manipulate matchups, positioning, and substitutions to tilt each confrontation before the ball is thrown.
Scoring at a glance
Core rules
The strike zone and the count
Every plate appearance is governed by the count of balls and strikes. The strike zone is the space over home plate between the batter's knees and the midpoint of the torso. A pitch in the zone, or one the batter swings at and misses, is a strike; three strikes make a strikeout. A pitch outside the zone that the batter does not offer at is a ball; four balls earn a walk to first base. Foul balls count as strikes except on a two-strike count, when they merely prolong the at-bat.
Hits and reaching base
A batter who puts the ball in play and reaches base safely records a hit, classified as a single, double, triple, or home run by the number of bases reached. Batters can also reach on a walk, a hit-by-pitch, or a fielding error. A home run, most often a ball hit over the outfield fence in fair territory, lets the batter and any runners score freely. Batting average, hits divided by official at-bats, remains the traditional measure of a hitter, though on-base percentage now rivals it.
Making outs
The defense ends a batter's or runner's turn by recording an out. Common outs include the strikeout, the flyout when a batted ball is caught before it lands, and the groundout when a fielder throws to first ahead of the runner. On a force play, a runner obligated to advance can be retired by a fielder touching the base with the ball. Runners not forced must be tagged with the ball. Three outs retire the side and switch the teams between offense and defense.
Base running
Once a batter becomes a runner, the goal is to circle the bases and reach home. Runners may attempt to steal a base as the pitcher delivers, advance on a hit, or tag up and run after a caught fly ball. They must touch each base in order and may be forced to retreat if a fly is caught. A runner is safe if he reaches the base before being tagged or forced out. Aggressive, intelligent baserunning can manufacture runs without a hit.
Fair and foul territory
Two foul lines run from home plate through first and third base to the outfield fence, dividing the field into fair and foul territory. A batted ball settling in fair territory is live and in play. A ball that lands foul is dead and, unless caught for an out, counts as a strike only if the batter has fewer than two strikes. Down the lines, the foul poles mark whether a long drive is a fair home run or a foul ball, a distinction that can decide games.
The pitcher and the mound
The pitcher works from a rubber atop a mound whose front edge sits 60 feet 6 inches from home plate, ten inches above the field. He must contact the rubber during delivery and, with runners on base, obey rules against deceptive movements. Pitchers mix fastballs, breaking balls, and changeups to disrupt a hitter's timing. Because the physical toll is severe, starters typically work every fifth day while relievers handle short, high-intensity stints. A modern pitch clock now limits the time between deliveries.
The lineup and the designated hitter
Each team submits a batting order of nine hitters who bat in fixed rotation; when the ninth hits, the order returns to the top. A player removed from the game cannot return. Since 2022 both major leagues use the designated hitter, a tenth player who bats in place of the pitcher without playing the field. The universal DH ended a decades-long rules split between the American and National Leagues and, in most cases, keeps pitchers out of the batter's box entirely.
Fouls & penalties
The balk
With runners on base, a pitcher who begins his delivery and then interrupts it, or who fails to come to a complete stop in the set position, commits a balk. The penalty awards each runner one base, since the move is meant to deceive them. Balks are among the game's most technical infractions, hinging on tiny movements of the shoulder, foot, or glove that umpires must judge in real time.
Interference
Interference occurs when a player illegally impedes an opponent making a play. A batter who obstructs the catcher's throw, a runner who alters a fielder's attempt on a batted ball, or a spectator who reaches onto the field can all be called for it. The usual penalty is an out on the offending player and the return of other runners, though the specifics depend on who interfered and when.
Obstruction
Obstruction is the defensive counterpart to interference: a fielder without the ball who blocks a runner's path is guilty of it. Umpires award the runner the base he would likely have reached, protecting his right to run the bases unimpeded. Collisions at home plate and second base drew rule changes in the 2010s to reduce injuries, sharpening how obstruction is enforced on catchers and middle infielders.
Hit by pitch
A batter struck by a pitch outside the strike zone, who attempts to avoid it, is awarded first base. The rule discourages pitchers from throwing at hitters, though brushback pitches near the body remain a tense part of the inside game. Deliberate beanballs can trigger warnings, ejections, and bench-clearing confrontations, and umpires may eject a pitcher judged to have thrown intentionally.
Pitch clock and timing violations
Introduced to the major leagues in 2023, the pitch clock gives a pitcher fifteen seconds to deliver with the bases empty and, since 2024, eighteen with runners on. A violation adds a ball to the count; a batter not ready in time is charged a strike. Related rules limit pickoff attempts and mound disengagements, and the changes cut roughly half an hour from the average game in their first season.
Match format
A regulation game is nine innings long. The visiting team bats in the top of each inning and the home team in the bottom. If the home team leads after the visitors bat in the ninth, the game ends without the home half being played. If the score is tied after nine, the game goes to extra innings, played until one side leads at the end of a complete inning. In the traditional game there is no clock and no limit on how long a tie can persist.
Since 2020, most professional leagues place a runner on second base to start each extra inning, a rule that hastens resolution and reduces marathon games. A game called early for weather is official once five innings are complete, or four and a half if the home team leads. Championships are decided over best-of-seven series in Major League Baseball, so a team must win four games to take a pennant or the World Series, rewarding depth of pitching over any single hot night.
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