I used to use a slightly longer schooling whip on my rather lazy old boy, a light touch on his flanks occasionally would keep him walking on rather than just plodding and was also used to keep direction if you were cantering as he would sometimes veer sideways or if there was something on the verge and he wanted to go out into the road. Jockeys mostly use the whip in races flapping them in the air alongside the horse to encourage them on and also as someone else said to keep them going straight, you will often hear the commentator say they have changed their whip to the other hand if the horse is too near another and they need to make it move over. There is a rule on the amount of times a jockey can use one actually making contact with the horse. Although I know there is a need for a jockey to carry a whip in a race for these reasons I think there is nothing finer than seeing a good jockey win a race using hands and heels and riding a finish. Having ridden point to pointers and exercised NH horses who often have no manners (or brains!) I would not want to ride one without at least having a whip to fall back on.