contact angle of the racket can be more easily varied. Unlike the two aforementioned techniques, sidespin causes the ball to spin on an axis which is vertical, rather than horizontal. The axis of rotation is still roughly perpendicular to the trajectory of the ball. In this circumstance, the Magnus effect will still dictate the curvature of the ball to some degree. Another difference is that, unlike backspin and topspin, sidespin will have relatively very little effect on the bounce of the ball, much in the same way that a spinning top would not travel left or right if its axis of rotation were exactly vertical. This makes sidespin a useful weapon in service, because it is less easily recognized when bouncing, and the ball "loses" less spin on the bounce. Sidespin can also be employed in offensive rally strokes, often from a greater distance, as an adjunct to topspin or backspin. This stroke is sometimes referred to as a "hook". The hook can even be used in some extreme cases to circumvent the net when away from the table. Corkspin Players employ this type of spin almost exclusively when serving, but at the professional level, it is also used from time to time in the lob. Unlike any of the techniques mentioned above, corkspin (or "drill-spin") has the axis of spin relatively parallel to the ball's trajectory, so that the Magnus effect has little or no effect on the trajectory of a cork-spun ball: upon bouncing, the ball will dart right or left (according to the direction of the spin), severely complicating the return. In theory, this type of spin produces the most obnoxious effects, but it is less strategically practical than sidespin or backspin, because of the limitations that it imposes upon the opponent during their return. Aside from the initial direction change when bouncing, unless it goes out of reach, the opponent can counter with either topspin or backspin. A backspin stroke is similar in the fact that the corkspin stroke has a lower maximum velocity, simply due to the contact angle of the racket when producing the stroke. To impart a spin on the ball which is parallel to its trajectory, the racket must be swung more or less perpendicular to the trajectory of the ball, greatly limiting the forward momentum that the racket transfers to the ball. Corkspin is almost always mixed with another variety of