The optimal area on the racquet's string bed where contact produces the cleanest, most powerful, and most controlled shot. Hit the sweet spot and the ball launches with minimal vibration and maximum efficiency. Miss it and you feel the impact in your wrist. Larger racquet heads have bigger sweet spots. The sound difference between a sweet spot hit and an off-center hit is immediately recognizable.
"Clean contact, right on the sweet spot. You can hear it. That ball isn't coming back."