Let’s talk about the ball this month.
Why is it a good idea to mark your ball? Identification!
It will help eliminate the possibility of hitting a wrong ball. Which is (match play) loss of hole, (rule15-3a) stroke play (rule15-3b) two stroke penalty.
What is the penalty for hitting a ball during a practice swing? DEPENDS!!!
If the ball is not in play, such as only on the tee box. A player makes a practice swing and the ball falls of the tee or moves from original spot via an iron. There is NO penalty as the ball was not in play and the player did not make a stroke with the intension to hit the ball. (rule 18-2/19)
On a putting green or through the green. It’s a one stroke penalty and the ball must be replaced. (rule 18-2/20)
A player makes a practice swing and loose impediments cause the ball to move. Did the player cause the ball to move under the rules of golf? YES, because (rule 18-2/20.5) states that it is reasonably foreseeable that a practice swing will move loose impediments. The player incurs a One stroke penalty and the ball must be replaced.