When must a player mark their ball?

A player must mark their ball when play is stopped for any reason to ensure that the position of the ball is preserved accurately and to avoid any potential disputes. Marking the ball involves placing a marker, such as a coin, directly behind the ball on the putting green, which allows the player to lift the ball without losing its position. This practice is paramount in various situations such as when a player is asked to mark their ball to allow another player to take their shot or when weather conditions necessitate a stoppage in play.

The other scenarios mentioned do not generally require marking the ball. For instance, although marking might occur before putting or teeing off for specific reasons, it is not mandated as a general rule in those contexts. Marking at the start of the round is unnecessary, as there would be no prior play to require a marking. Therefore, marking during any stoppage ensures adherence to the rules and fair play on the course.