Rules of Golf

Golf Rule 18 - Ball at Rest Moved

BALL AT REST MOVED: to utilize this rule to your benefit you must know:
(i) if a ball leaves its position an comes to rest in another place, it has been deemed to have moved.
(ii) a ball is addressed when the player has taken his stance and also grounded his club. The exception is in a hazard. A player has addressed the ball in a hazard when he has taken his stance by placing his feet in a preparatory position for his stroke without grounding his club.

BALL MOVED BY THE PLAYER, THE PLAYER'S PARTNER, THE SIDES EQUIPMENT, OR THE PLAYER'S CADDIE--a player's ball must not be lifted, touched purposely, or moved unless a rule permits except with a club in the act of addressing.

PENALTY--one stroke and the ball must be replaced.

EXCEPTIONS (no penalty) if the ball is moved by any of the above:
(i) the ball moves in the process of lifting or replacing.
(ii) the ball moves in the process of measuring to determine correct order of play.
(iii) the ball moves in the process searching for it in a hazard or in an abnormal ground condition.
(iv) the ball moves in the process or removing a loose impediment on the putting green.
(v) the ball moves while moving a movable obstruction.
(vi) the ball moves in the process of repairing ball marks or hole plugs.

BALL MOVED AFTER IT'S ADDRESSED--when a player's ball has been moved after being addressed by the player the player incurrs a one-stroke penalty. The ball must be replaced unless the movement occurred after the swing began, and doesn't discontinue the swing.
NOTE--don't be confused, if the ball moves during the backswing, there is still a penalty stroke even though the swing is continued.

BALL MOVED AFTER LOOSE IMPEDIMENT IS TOUCHED:
(i) there is no penalty if the ball is on the putting green and is moved in the process of touching a loose impediment.
(ii) through the green, the player receives a one-stroke penalty and the ball must be replaced if the ball moves after a loose impediment lying within one club length of the ball is touched by the player, the player's partner, or their caddies.
NOTE--if the player's ball is in a hazard the player may not touch or move a loose impediment in the same hazard.

BALL MOVED BY OPPONENT, OPPONENT'S CADDIE, OR OPPONENT'S EQUIPMENT IN MATCH PLAY:
DURING SEARCH--no penalty is incurred to either side if during a search the player's ball is moved. The ball must be replaced by the player.
OTHER THAN DURING SEARCH--the opponent receives a one stroke penalty and the ball must be replaced by the player.

BALL MOVED BY FELLOW COMPETITOR, FELLOW COMPETITOR'S CADDIE OR EQUIPMENT IN STROKE PLAY: no penalty is incurred and the player must replace his ball.

BALL MOVED BY ANOTHER BALL: (pay attention!!) a ball that's at rest and in play is moved by another that's in motion (after a stroke) the ball that's moved must be replaced.
NOTE--a ball that is required to be replaced and is not, the player would lose the hole in match play and a two stroke penalty in stroke play for playing from a wrong place. No additional penalty will apply according to this rule.
NOTE--if it's impossible to determine where a ball should be replaced, must then be dropped as close to the original spot as possible.
NOTE--a ball that to be replaced that cannot be immediately recovered another ball may be substituted.