In baseball, a pitch is the act of throwing a baseball toward home plate to start a play. The term comes from the Knickerbocker Rules. Originally, the ball had to be literally "pitched" underhand, as with pitching horseshoes. Overhead throwing was not allowed until 1884.

The biomechanics of pitching have been studied extensively. The phases of throwing include windup, early cocking, late cocking, early acceleration, late acceleration, deceleration, and follow-through.

Pitchers throw a variety of pitches, each of which has a slightly different velocity, trajectory, movement, hand position, wrist position and/or arm angle. These variations are introduced to confuse the batter in various ways, and ultimately aid the defensive team in getting the batter or baserunners out.

To obtain variety, and therefore enhance defensive baseball strategy, the pitcher manipulates the grip on the ball at the point of release. Variations in the grip cause the seams to "catch" the air differently, therefore changing the trajectory of the ball, making it harder for the batter to hit.

The fastball is the most common pitch in baseball, and most pitchers have some form of a fastball in their arsenal. It is basically a pitch thrown very fast, some with movement, some without. The cut fastball, split-finger fastball and forkball are variations on the fastball with extra movement, which are sometimes called sinking-fastballs because of the trajectories. The most common fastball type pitches are:

• Four-seam fastball (rising fastball)
• Two-seam fastball
• Cutter
• Split-finger fastball
• Forkball
• Sinker