This is the way to hold the racquet for the serve, volley, sliced backhand and smash. It is known as the chopper grip, because it is the way you would hold an axe. It allows you to swing the racket ...
Place the palm of your hand on top of the handle then move the racket inwards a quarter turn. The thumb should fall diagonally across the back of the grip, though some players wrap it all the way ...