Every professional baseball pitcher wants to throw the ball so the batter can’t hit it.
There are lots of ways to do that.
One way is for the pitcher to throw the ball so that, after it leaves his hand, it “dips down.” That’s known as a curve ball.
Curve balls are tricky to throw. One reason is that it’s hard to grip the smooth, slippery ball.
Last week, a pitcher from the Yankees baseball team was caught using sticky pine tar so he could grip the ball better.