What is topspin in tennis?
The spinning ball drags air unevenly, which pushes it downward: the Magnus effect. That lets you hit higher over the net and still land inside the baseline, which is why topspin is the margin shot.
TRACED · NADAL'S FOREHAND
Contact
You make it by brushing up the back of the ball with a low-to-high swing and a near-vertical racquet face.
Questions
Why does topspin make the ball dip?
The spin creates a downward Magnus force, so the ball curves down faster than gravity alone would pull it.
Is topspin safer than a flat shot?
Usually. A heavy topspin ball can clear the net by more and still land in.