The Diamond
The infield is a square that looks like a diamond when you stand at home plate — ninety feet on each side. Home plate sits at the bottom corner, with first base to the right, second base straight ahead, and third base to the left. A batter becomes a runner at home and must travel to first, then second, then third, and back home to score.
The Mound and the Battery
At the center of the infield is the pitcher’s mound, a low raised circle with a rubber slab exactly sixty feet, six inches from home plate. The pitcher throws from there to the catcher, who crouches behind home plate. Together they are called the battery, and they are involved in every single pitch of the game.
Fair and Foul
Two white lines run from home plate past first and third base all the way to the outfield fence: the foul lines. A ball that stays in the wedge between them is fair and in play; a ball outside them is foul. The grass beyond the infield dirt is the outfield, bounded by a fence that can sit anywhere from about 300 feet down the lines to 435 feet to dead center.
The Equipment
Pitchers throw a cork-and-leather ball about three inches across. Hitters swing a rounded wooden bat. Every fielder wears a leather glove; the batter and catcher wear helmets, and the catcher adds a mask, chest protector, and shin guards.
Why the Geometry Matters
No two outfields share the same shape or size. That is unique among major sports, and it means the venue itself changes how a game plays — a theme we return to when we reach park factors.