what is a 4 seam fastball

A four-seam fastball is a pitch in baseball that is usually the hardest ball thrown by a pitcher. It is a member of the fastball family of pitches and is designed purely for velocity, traveling to the batters box with little or no "break" from straight-line flight. The ball is gripped with the index and middle fingers set on or across a line (cross-seam) of the "horseshoe" seam that faces outward, away from the pitchers body. A four-seam fastball differs from other fastballs, such as two-seamers or sinkers, in that it shows greater vertical movement, less sink, and a higher average velocity. A four-seam fastball with high spin is often described as a "rising fastball," because it resists gravity slightly longer, making it look to the hitter like it is rising. The four-seam fastball is typically the “staple” of a pitcher’s arsenal, and it is often the fastest pitch that a pitcher will throw. It maintains a good amount of vertical break and slight amounts of horizontal break. Being a staple in a pitcher’s arsenal, it’s important to be able to effectively tunnel this pitch with the off-speed pitches in your arsenal and create deception against the hitter.