The pitcher will attempt to throw balls that are difficult to hit, while still remaining inside the strike zone where the batter is expected to try to hit them. The batter does his or her best to quickly judge whether or not the ball is safe to hit, and then swings at it. If the batter connects and the ball doesnt cross the foul lines, its in play.Pitchers often use fastballs, curveballs, changeups, and sliders to confound batters. The fastball is what it sounds like very fast as is the curveball. A changeup involves the pitcher pretending to throw a fastball but actually throwing a much slower pitch, confusing the batters sense of timing. A slider is a difficult to throw ball that combines most of a fastballs speed with a curveballs lateral movement.