Backward rotation on the ball, also called underspin. Created by hitting down and through the back of the ball with an open racquet face. Backspin makes the ball float more through the air and stay low after bouncing. Used on slice groundstrokes, drop shots, and chip returns. A well-executed backspin shot skids through the court and forces the opponent to bend low to return it.
"Heavy backspin on the drop shot. The ball bounces and actually spins back toward the net. That's disgusting."