There are 2 main back hand grips: the Basic grip and the Power Grip.
The Basic Grip gives a high degree of control, since the index finger along the rim helps with direction and the middle finger supporting the disc supplies stability. On the down side, there are only two fingers gripping the rim, and this leads to much less power than most of the other grips. Most of the power in a grip comes from the ripping of the disc off the end of the index finger.
The Power grip is when all fingers are gripping the rim tightly, and there are no fingers supporting the disc. This means there is a considerable loss of control, since the release point is much harder to judge. A fair degree of control can be regained through practice, and the loss is offset in some ways by the large power gain produced by the disc ripping off the end of the index finger. This grip does however make it harder to throw the high backhand as there is no support for the sharp upward push on the disc just prior to release. In general, the tighter the grip, the more spin which is able to be imparted to the disc, making the frisbee unaffected by wind.