Baseball

Overview

Two teams of nine alternate batting and fielding across nine innings. The batting side scores by getting runners around four bases; the fielding side tries to record three outs.

This entry is checked against the Official Baseball Rules, 2026 Edition, published by the Office of the Commissioner of Baseball. Rule numbers below are the OBR's. Major League Baseball also runs some rules through separate regulations that aren't in the Official Baseball Rules, and the page says where.

1. The field

A diamond with bases 90 feet apart: first, second, third and home plate. The pitcher stands on a mound 60 feet 6 inches from home.

Fair territory extends between the two foul lines; outfield fences vary enormously by ballpark, which is unusual among major sports.

2. Structure

Nine innings, each split into a top half and a bottom half. The visiting team bats first.

A half-inning ends when the fielding side records three outs.

If the home team leads after the top of the ninth, the game ends immediately — they do not bat. Tied games go to extra innings, played until one side leads at the end of a completed inning, or the home team scores the winning run.

Every extra half-inning starts with a runner on second base (Rule 7.01(b)(2)). The runner is the player who batted immediately before that inning's leadoff hitter, or a pinch-runner for them.

3. The count

The pitcher throws to the batter. Every pitch is a ball or a strike.

Outcome	Result
Three strikes	Batter is out — a strikeout
Four balls	Batter walks to first base

A strike (the OBR definition) is a pitch that:

• is swung at and missed;
• is not swung at, if any part of the ball passes through any part of the strike zone;
• is hit foul with fewer than two strikes;
• is bunted foul;
• touches the batter as they swing, or touches them in flight in the strike zone;
• becomes a foul tip.

A foul ball cannot be the third strike — except on a bunt attempt, and except for a foul tip caught cleanly by the catcher.

The strike zone is the area over home plate from a line midway between the top of the shoulders and the top of the uniform pants down to the hollow beneath the kneecap. It is judged from the batter's stance as they prepare to swing at the pitch, not how they stand while waiting.

4. Getting out

• Strikeout — three strikes
• Flyout — a batted ball caught before it lands
• Groundout — the fielding side gets the ball to first base before the runner
• Force out — a runner forced to advance is beaten to the base
• Tag out — a runner off a base is touched with the ball
• Fly rule — the infield fly rule protects runners from a deliberate drop

5. Scoring

A run scores when a player touches first, second, third and home in order.

A home run is a fair ball hit over the outfield fence — all runners on base score, so a home run with the bases loaded is a grand slam, worth four.

6. Baserunning

Runners may steal a base at any time the ball is live, at their own risk.

A runner is forced to advance when the batter becomes a runner and all bases behind are occupied. Forced runners can be put out by a fielder simply touching the base.

Tagging up — on a caught fly ball, a runner must return to their base and touch it before advancing.

7. Pitching restrictions

A balk is an illegal deceptive motion by the pitcher with runners on base; all runners advance one base.

The shift limit is in the rules. Rule 5.02(c), "Infielder Positioning": when the pitch is released, the defence must have at least four players besides the pitcher and catcher with both feet in front of the outer edge of the infield dirt, at least two of them entirely on each side of second base. The two infielders on each side can't swap sides for the rest of the inning.

The pitch clock is not in the Official Baseball Rules. The 2026 edition contains no pitch timer, and no limit on pickoff attempts. Both are MLB regulations published separately, which haven't been checked for this page, so this entry gives no figures for them. Lower levels of baseball may not use them at all.

Commonly argued

• A foul ball is a strike, but never the third strike — unless bunted, or caught as a foul tip.
• The home team does not bat in the ninth if already ahead.
• Extra innings start with a runner on second. That's in the Official Baseball Rules themselves.
• A pitch is a strike if any part of the ball passes through any part of the zone.
• "Tie goes to the runner" isn't in the rulebook. The Official Baseball Rules contain no rule for a tie at a base.
• The pitch clock isn't in the Official Baseball Rules. It's a separate MLB regulation.
• The shift limit is in them: two infielders on each side of second base, all four on the dirt, when the pitch is released.
• A home run counts every runner on base, so the maximum is four.
• The batter is out on a caught fly regardless of where it lands, fair or foul.