2019 has seen a lot of changes in the rules for Golf tournaments. Below you find a summary of the key changes as well as some video links for those who rather to watch than read (Many thanks to Mark Broughton for putting them together for us).

Rules Topic Description of change / New rule
Summary of 20 most important changes Video LINK.
Flag stick in or out, which is the better choice Video LINK.
Player accidentally moves his or her ball during search No penalty.
Player accidentally moves his or her ball or ball-marker on the putting green No penalty.
How to replace a ball lying off the putting green when it moves and its exact original spot isn’t known Replace the ball on its estimated spot; if that spot was on, under or against attached natural objects, replace the ball on that spot on, under or against those objects.
Player’s ball in motion accidentally hits the player, the person attending the flagstick or the attended or removed flagstick No penalty.
Player accidentally hits the ball more than one during a stroke. No penalty.
Where a ball must be dropped Drop in a defined relief area. Drop in the defined relief area.
Where a dropped ball must come to rest. The ball must come to rest in the relief area where it was dropped. If the ball comes to rest outside of the relief area, the player will drop a second time in the relief area. If the ball again comes to rest outside the relief area, the player will place it where the ball first touched the ground on the second drop.
Measuring the size of the relief area where a ball must be dropped and played. The relief area is measured by measuring 1or 2 club lengths (longest club, other than a putter).
How to drop a ball The ball must be dropped straight down from knee height (the height of the player’s knee when in a standing position).
Time allowed for a ball search A ball is lost if not found in three minutes.
Substituting ball when taking relief A player may always substitute a ball when taking relief.
Taking relief for a ball embedded in its own pitch-mark. A player may take relief without penalty for an embedded ball anywhere in the “general area” (new term for “through the green”), unless a Local Rule has been adopted restricting relief only to areas cut to fairway height or less.
Replacing a ball on the putting green when it moves from its spot after it already had been lifted and replaced. The ball must always be replaced on its original spot, even if it was blown by the wind or moved for no clear reason.
Repairing damage on the putting green A player may repair almost any damage (including spike marks and animal damage but not including natural imperfections) on the putting green.
Player touches the line of putt or touches the putting green in pointing out a target. No penalty, so long as doing so does not improve the conditions for the player’s stroke.
Putting with an unattended flagstick left in the hole No penalty if a ball played from the putting green (or anywhere else) hits the unattended flagstick in hole.
Player moves loose impediment, touches the ground with hand or club or grounds the club in a penalty area when the ball is in the penalty area. No penalty.
Elimination of the opposite side relief option for red penalty areas A player is no longer allowed to take relief from a red penalty area on the opposite side from where the ball last entered that penalty area, unless the Committee adopts a Local Rule allowing it.
Player moves or touches a loose impediment in a bunker when the ball is in the bunker No penalty.
Player touches sand in a bunker with his or her hand or a club when the ball is in the bunker No penalty except when a player touches sand (1) with his or her hand or club to test the conditions of the bunker, (2) in making a practice swing, (3) with the club in the area right behind or in front of the ball or (4) in making the backswing for the stroke.
Unplayable ball relief options A player may take relief outside the bunker back on the line from the hole through where ball was at rest for 2 penalty strokes. Current rule: No relief outside the bunker (other than in playing from where the player’s last stroke was made).
Use of distance-measuring devices (DMDs). The use of DMDs is allowed, unless a Local Rule has been adopted prohibiting their use.
Recommendations on how to play promptly Recommends that players make each stroke in no more than 40 seconds, and usually in less time.
Playing out of turn in stroke play No penalty (as today), and “ready golf” is encouraged when it can be done in a safe and responsible way.
New alternative form of stroke play New rule: A new “Maximum Score” form of stroke play is recognized, where a player’s score for a hole is capped at a maximum score (such as two times par, a fixed number or net double bogey) that is set by the Committee.
Changes to Out of Bounds (OOB) rules The rules remain the same for OOBs in 2019; there is no option under the new rules to drop a ball, you must play another ball from the place where the original shot was taken.