<p>The slider is part fastball, part breaking ball. It&#39;s more like a fastball because it&#39;s more effective the faster it&#39;s thrown. The slider breaks late, meaning close to the batter, which makes it one of the most effective <a href="https://www.thoughtco.com/fundamentals-of-pitching-2710404" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="1">pitches</a> in baseball.</p><p>The grip of slider is similar to a two-seam fastball, with the middle finger and index finger across the two widest seams.</p><p>The difference is that the fingers should be slightly off-center, toward the outside of the ball, like you&#39;re just holding the outside third of the ball. Your thumb should be tucked under the ball, with the ring and pinkie finger off to the side.</p><p>Apply pressure to the ball with your thumb and middle finger.</p><p>Like a curveball, a pitcher must keep their wrist loose when throwing a slider.</p><p>Throw the ball the same way you&#39;d throw a fastball. Imagine cutting through the ball with your middle finger as you throw the pitch. The ball should roll off your hand off your index finger, which is what gives the slider its spin.</p><p>As it is with all of pitching, keeping your intentions secret is a big part of the battle.</p><p>Keep the ball hidden in your glove when you&#39;re throwing, or you might tip off the batter (or a baserunner or base coach) what pitch you&#39;re throwing.</p>Wind up normally and throw. Don&#39;t forget to follow through. When you don&#39;t follow through, the ball will likely stay high.