In baseball, the home plate is a five-sided rubber slab and serves two purposes. It's the final base a base runner must touch in order to score a run. And it is also used by the umpire to determine the width of the strike zone when the pitcher delivers the ball.
Home plate is pentagon-shaped, positioned with the narrow point facing directly to the rear. The spot where the edges come together to form a point is the lowest tip of the baseball "diamond", from which the straight foul lines originate. When determining whether a pitch is in the strike zone, the dimensions of home plate define the horizontal axis of the zone. Home plate was originally constructed of wood, stone or metal, but deemed too dangerous and eventually converted to rubber.
Home plate is defined as "home base" for the purpose of rules.