dirt no higher than 10 in (25.4 cm). Near the center of the mound is the pitching rubber, a rubber slab positioned 60 ft 6 in (18.4 m) from home plate. The pitcher must have one foot on the rubber at the start of every pitch to a batter, but the pitcher may leave the mound area once the ball is released. At the college/professional level, baseball is played in nine innings in which each team gets one turn to bat and tries to score runs while the other pitches and defends in the field. High school baseball plays seven innings and Little League uses six-inning games. An inning is broken up into two halves in which the away team bats in the top (first) half, and the home team bats in the bottom (second) half. In baseball, the defense always has the ball—a fact that differentiates it from most other team sports. The teams switch every time the defending team gets three players of the batting team out. The winner is the team with the most runs after nine innings. If the home team is ahead after the top of the ninth, play does not continue into the bottom half. When this happens, an X is put on the scoreboard for the home team's score in the ninth inning. In the case of a tie, additional innings are played until one team comes out ahead at the end of an inning. If the home team takes the lead anytime during the bottom of the ninth or of any inning after that, play stops and the home team is declared the winner. This is known as a walk-off. The basic contest is always between the pitcher for the fielding team and a batter. The pitcher throws—pitches—the ball towards home plate, where the catcher for the fielding team waits (in a crouched stance) to receive it. Behind the catcher stands the home plate umpire. The batter stands in one of the batter's boxes and tries to hit the ball with a bat. The pitcher must keep one foot in contact with the top or front of the pitcher's rubber—a 24×6 in (61×15 cm) plate located atop the pitcher's mound—during the entire pitch, so he can take only one step backward and one forward in delivering the ball. The catcher's job is to receive any pitches that the batter does not hit