Hitting a baseball is hard. Really, really hard. You’re good at it if you fail 7 out of 10 times. Part of the way you get good at hitting baseballs is by recognising the spin or rotation of the red seams on the white outside of the ball. This article from CBS takes a look at five common pitches and what they look like to the batter.
Credit for the original piece goes to an unknown person, I don’t think it was the article’s author.