A slider is a type of pitch in baseball that is thrown with a wrist snap and spin, and is generally perceived as somewhere between a cutter and a curveball. It is a breaking pitch that tails laterally and down through the batters hitting zone, and is thrown at a speed that is lower than a fastball, but higher than the pitchers curveball). A slider is meant to be slightly more deceptive than a curveball because it is thrown harder and has spin that more closely resembles a fastball, although it doesnt create as much overall movement. The difference between a slider and a curveball is that the curveball delivery includes a downward yank on the ball as it is released in addition to the lateral spin applied by the slider grip. The slider is released off the index finger, while the curveball is released off the middle finger). If the pitcher is snapping his wrist as he throws, and the movement is more downward than sideways, then he is probably throwing a curveball or slurve, and not a true "slider").
To throw a slider, the pitcher needs to maintain a consistent release point as the rest of their pitches. If a pitcher is completely changing their arm angle to be able to throw this pitch, it will lose all of its deception and value to the pitcher’s arsenal. Some cues that can help pitchers throw a slider include "come around the ball" and "3 o’clock to 9 o’clock".
