As a pitcher, you have two different types of fastballs: the four-seam and two-seam. The fastball is your main pitch to consistently pitch in the zone and throw strikes.
For the four-seam fastball, place two fingers across the seams with your thumb underneath. If you rotate the ball 360 degrees towards home plate from this position, you can count the four seams; hence, a four-seam grip. For smaller hands, it is natural to use three fingers on the seam. The four-seam fastball is a great pitch for maintaining control and throwing with velocity to your target. When throwing this pitch in the zone you will create weak contact and ground balls for your defense to field.
The other fastball grip is a two-seam fastball. For the two-seam fastball grip, place two fingers close together, in between the seams, with your thumb underneath. From this position, rotate the ball 360 degrees and count the seams. There should be two seams that are part of that rotation. The two-seam fastball has a little more movement to the arm side. That means the ball will fade to the right on its way toward the plate if you’re a right-handed pitcher. If you’re a lefty, the ball will break toward the left side of the plate. As it moves in that direction, it will lose a bit of velocity and move down in the zone. Generally, pitchers will have slightly less control with this pitch because of that movement.
Remember, it is important to develop your fastball early and often. When you pitch to contact that will help your defense make more plays and, ultimately, help you win more ball games.