Googly is a term associated with leg spin bowling. It is a deceptive delivery and most of the batsman find it difficult to read a Googly.
The normal delivery of a leg spinner is the one that pitches and spins away towards the off side - in the case of a right-hander. In other words, the ball after pitching moves away from the right-hander. The Googly, on the other hand, is the delivery of a leg spinner that comes in after pitching. The specialty, however, is that the delivery action for a Googly is very similar to that of a normal leg spinning delivery. This is the reason why the batsman ends up getting foxed.
In order to be able to bowl a Googly the bowler will have to deliver the ball from the back of his palm. It is a very difficult art and is mastered by only a few.
Some of the contemporary leg spinners who successfully bowl the Googly are Shane Warne of Australia and Mustaq Ahmad of Pakistan.