Pitcher's mound
On a baseball field, the pitcher's mound is a raised section in the middle of the diamond where the pitcher stands when throwing the pitch.
In Major League Baseball, a regulation mound is 18 feet (5.5 m) in diameter, with the center 59 feet (18.0 m) from home plate, on the line between home plate and second base. The pitcher's plate or rubber is 18 inches (45.7 cm) behind the center of the mound, making it 60 feet 6 inches (18.4 m) from the plate. Six inches (15.2 cm) in front of the rubber the mound begins to slope downard. The rubber is also never more than ten inches (25.4 cm) high, although previously to 1969 it was often at 16 inches (40.6 cm) or even 20 inches (50.8 cm).
A pitcher will push off the rubber with his foot in order to gain velocity toward home plate when pitching. In addition, a higher mound generally favors the pitcher over a lower mound. With the height advantage, the pitcher gains more leverage and can put more downward velocity on the ball, making it more difficult for the batter to strike the ball squarely with the bat. Thus, the lowering of the mound in 1969 is thought to be a contributing factor to the hitting surge seen in modern baseball.
A pitcher's mound is difficult for groundskeepers to maintain. On youth and amateur baseball fields, the mound may be much different than the rulebook definition due to erosion and repair attempts. Even in the major leagues, each mound gains its own character, as pitchers are allowed to kick away pieces of dirt in their way, thereby sculpting the mound a bit to their preference.