The drift is where, during the pause section, of either the forward or backward casts, the rod is moved in the same direction the line is travelling. My main interest here is with the back cast: after the stop make a small movement backwards and upwards with the hand, or perhaps concentrate on slightly lifting the elbow. There are four main reasons to learn the drift:-

1. It improves timing

2. It cushions the tip of the rod

3. It leaves you in a better position to start the forward cast - remember that for most backcasts we are simply flicking the tip, whereas for the forward cast we may well want to bend the butt. The first is a small stroke: the second a large stroke. In other words you have to relocate rod position to accommodate that increased stroke.

4. It helps avoid tailing loops: a very common problem casters get into is throwing a wickedly tight loop on the backcast which then straightens and forces the rod to bend backwards, forcing the caster to start the cast with a bend rod. This often causes the tip to dip under the straight line path and creates tailing loops. Apart from drifting backwards there are only two other ways to get around this problem: the first is to throw poorer quality loops (!), the second is to race the forward cast - in other words start with the bent rod and hope to increase the bend. Now although there is a slight possibility that this slight bend can be useful in certain circumstances, namely to competition casters (although I'm dubious about this, but it can't be completely ruled out) it is very difficult to control and on the whole a much better technique is to avoid this with the backwards drift.

Learning to drift backwards often turns an intermediate caster into a good caster almost instantly - always assuming the other things are working fairly well together.

Drifting on the forward cast is also important, however purely as a means of cushioning the rod tip.

Long casters allow their backcasts to straighten out more fully - another great reason for learning the back-drift.

Here's an article: on Drift