Baseball 101: 1-2-3 inning

A 1-2-3 inning refers to an inning in which a pitcher retires the batters in consecutive order.  In a 1-2-3 inning, no batters reach base.  This means that if the first batter reaches base, and the second batter grounds into a double play, the inning does not qualify as a 1-2-3 inning, even if the third batter gets put out.  Each batter must be put out, either by strikeout or defensive put-out, without safely reaching base before the next batter comes to the plate.

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