In baseball, "spin" refers to the rotation imparted on the ball during a pitch or hit, affecting its trajectory and behavior. Pitchers manipulate spin to create various effects, such as curveballs, sliders, and fastballs. The type of spin can significantly impact how the ball moves towards the batter, contributing to a pitcher's strategy to deceive and strike out opponents. Additionally, hitters analyze spin to adjust their timing and aim when hitting the ball. Mastery of spin is crucial for success in the game.