How Baseball Innings Work
Outs, innings and switching sides — a 5-minute hands-on for anyone new to baseball.
📖 In one sentence: when the defense gets the batting team out 3 times, the two teams switch between batting and fielding. Once both teams have batted, that's 1 inning. Repeat for 9 innings and the team with more runs wins!
Scoreboard: runs scored each inning stack up here. R = total runs.
How it works
Baseball splits into innings, and each inning has two halves. In the top half one team bats while the other fields; in the bottom half they swap. The fielding team's goal is to record 3 outs (a strikeout, a caught fly ball, and so on) — as soon as they do, the sides switch. When both teams have had their turn at bat, one inning is complete; a full game is 9 of them. While a team bats, hits move the batter and any runners around the bases (1st → 2nd → 3rd → home), and every runner who reaches home scores a run. This trainer runs a short 3-inning game so you can feel the rhythm: press "Bat!", watch the outs pile up, see the sides switch, and follow the runs stacking on the scoreboard. After a few games the play-by-play on TV — "bottom of the 7th, two outs, runner on second" — will finally make sense.
The structure from the top down
A game is nine innings. Each inning has two halves, called the top and the bottom. In the top half the visiting team bats and the home team fields; in the bottom half they swap. A half-inning ends when the fielding team records three outs, however many runs have been scored by then. When both halves are done, one inning is complete.
Outs are the currency of the game. A batter can be struck out, a batted ball can be caught before it lands, or a runner can be tagged or forced out before reaching a base. Three of those in any combination end the half-inning immediately, which is why a rally can be alive one moment and over the next.
Why the home team bats last
Batting in the bottom half is a real advantage, and the rule exists to give it to the home side. If the home team is ahead after the top of the ninth, the game simply ends — there is no need for them to bat at all. If they are behind, they get the last chance to respond, knowing exactly how many runs they need.
This is also why baseball has no clock. A team behind by ten runs in the ninth still gets its three outs, and a game cannot be run out. It is the reason comebacks are possible at any margin, and the reason a game can last three hours or five.
If the score is level after nine innings, play continues in extra innings until one team is ahead at the end of a complete inning. A tied game is unusual in professional baseball for exactly this reason.
The terms that come up constantly
- Strike — a pitch the batter swings at and misses, or one that passes through the strike zone untouched. Three strikes is an out.
- Ball — a pitch outside the strike zone that the batter does not swing at. Four balls and the batter walks to first base.
- Run — scored when a runner touches first, second, third and home in order. Runs, not hits, decide the game.
- Home run — a batted ball hit out of the field of play, letting the batter and every runner score.
- Inning — one complete cycle of both teams batting. Nine of them make a game.
Frequently asked questions
What exactly is an "inning"?
An inning is one full round where both teams get a turn to bat. The team batting first plays the "top" of the inning; the other team plays the "bottom". A standard professional game has 9 innings.
Why do the teams switch?
The fielding team switches to batting once it records 3 outs against the batting team. Outs come from strikeouts, caught fly balls, and other plays. Three outs end that half-inning immediately.
How are runs scored?
A runner scores 1 run by advancing all the way around the bases and touching home plate. Hits move the batter and existing runners forward — a home run scores the batter and every runner at once.
Is this a real game or a simplified model?
It's a simplified teaching model. It runs a quick 3-inning game and focuses on the core flow — outs, switching sides, innings and runs — so beginners can grasp the structure. Real baseball adds balls, strikes, stealing, fielding positions and much more.
Why are there 9 innings in a baseball game?
Early baseball wasn't timed by innings at all — games ended when one club reached a set number of runs, originally 21. In the late 1850s the rules were rewritten to fix games at 9 innings, matching the nine-player lineup, and that standard stuck. Amateur and youth leagues often play shorter games, commonly 6 or 7 innings.
What happens if the score is tied after the final inning?
The game goes to extra innings: both teams keep batting through full innings until one side leads at the end of a completed inning. Many professional leagues speed this up by starting each extra inning with a runner already on second base, and some leagues instead declare a tie after a set number of innings.