If your ball is buried, you may probe the sand and move loose impediments (pebbles, leaves, etc.) until a sufficient portion of the ball is visible to play a shot. If too much sand is removed, the ball must be covered up until only part of the ball is visible. (Rule 12-1)
You cannot ground your club or touch the sand with your hand to test the surface or to remove a loose impediment. But you can touch the sand to look for a buried ball, to prevent yourself from falling, to remove an obstruction (a soda can or cigarette butt, for instance) and to put down a club. However, these exemptions don't apply if, in doing so, you test the surface or improve your lie. The penalty is two shots in stroke play or loss of hole in match play. (Rule 13-4)
If you play a wrong ball from a bunker, you lose the hole in match play or incur a two-shot penalty in stroke play. (Rule 15-3)
Even during the backswing, you can't ground your club. (Rule 13-4)
Accidentally moving a loose impediment is OK as long as the impediment was not moved in making the backswing and you don't improve your stance, swing or the ball's lie. (Decision 13-4/13)
If your ball is in casual water, you may drop it in a dry area of the bunker (no penalty), no closer to the hole. If the bunker is under water, you may drop outside the bunker (penalty, one stroke), keeping the point where the ball lay between the hole and the spot on which the ball is dropped. (Rule 25-1)
If your ball moves as a result of shifting sand caused by taking a stance, add a penalty stroke and replace the ball. (Rule 18-2a)
__Q:__How many strokes do I have to give my dad when I play from the blue tees and he plays from the whites? My course handicap is 12, and his is 15, and the Course Rating is 70.5 from the blue and 69.0 from the white.
__A:__Your difference in course handi-caps is three shots, but you have to adjust your handicaps for the difference in the Course Rating. Your rating is 1.5 shots higher than Dad's. That rounds up to two shots, so you get 14 strokes (12+2) to his 15. Instead of giving him three shots, you give him only one, on the No. 1 handicap hole.
By Dean Knuth, Golf Digest Professional Advisor. Former senior director of the USGA handicap department, Knuth invented today's Course Rating and Slope system.