Will Hamilton: The third step of the serve is the backswing. Behind me and my stance, I am about to shadow the backswing.

But in this video, I only want you to focus on the hand that's holding the tennis racquet because we've already talked about the toss.

Now, to begin the backswing, I let my hitting arm drop down to my side. And, when this happens, the tennis racquet kind of looks like it is pointing at the court. And then from here, I begin to raise the racquet. But when I raise the racquet, initially my palm is going to stay facing the court. And, you can see that here, my palm is still pointed down.

Now, I continue to raise the tennis racquet until I get to this position here, where my tennis racquet and my arm look like an L. And, because it looks an L, this is commonly called the L position. And the other key here is that you have the tennis racquet pointed straight up in this sky.

So, let's watch that one more time from the stands. The racquet comes down to my side, and is pointing at the court. Then, I begin to raise it, my palm stays down initially, and I bring my arm and my tennis racquet up until I get to this position, which is commonly called the L position.

Let's watch Sacha Jones's backswing. Here she is in her stance, and she begins her backswing by dropping her arm and her tennis racquet down by her side so that the racquet is kind of pointed at the court. And, from here she begins to raise the tennis racquet, but if we freeze it now you can see that even though she is raising the tennis racquet, her palm stays facing the tennis court. She'll continue to bring the racquet up until the tennis racquet is pointed straight up into the sky. And for tennis racquet and her arm, now look very similar to an L. And again, that's why the relationship between her arm and her racquet now is called the L position. It looks like an L, and this is the position you want to get to at the completion of your backswing.

Let's look at a few pictures of John Isner, and see how he takes the tennis racquet back. In this first shot, John is in his stance. But in this next picture now, he has begun to take the racquet back by first, dropping his arm and the tennis racquet down by his side so that the tennis racquet is more or less pointing at the tennis court. Now, John has begun to raise the tennis racquet, but if we move in on the racquet and his hand, what you will see is that his palm is still facing down at the tennis court as he raises the tennis racquet. Finally, now John has completed his backswing by getting the racquet all the way back so that the racquet is now pointed up at the sky. And again, the relationship between his tennis racquet and his arm look like an L, and that's why this position John's in is called the L position.