The drop shot is an effective change-up shot when the opponent might have been expecting a push and stayed back a little. The drop shot keeps the ball very short and forces the opponent to quickly come forward to play the ball. This can force an error and give you the opportunity to attack.
Play the ball very soon after the bounce. Let it drop under your table tennis paddle and without much motion, use the rubber’s springiness to let the ping pong ball rebound back over the net. Keep it as low as possible.
The drop shot you use when someone makes you short serve it, then you make a drop shot that he cannot attack you after the served ball, and this is very important that you use a lot of feeling and this is, I think, different in top players and the standard players that have really good feeling for this drop shot ball. It’s very important sometimes when the opponent serve you that you make the drop shot and this keeps you safe against a very dangerous attack from your opponent.