How do you know if that's your ball?
The Rules of Golf impose a penalty of loss of hole in match play or two strokes in stroke play for playing a ball that is not yours. To protect yourself against this violation, the Rules allow, and even encourage you, to put an identifying mark on your ball (Rules 6-5 and 12-2).
One of the most common ways to put an identification mark on your ball is to use a SharpieÒ or some other permanent marker. You may use any color that you wish and you may put the mark or marks anywhere on the ball that you wish.
You may choose to mark the ball with your “lucky” markings which could include a charm, a number you are trying to shoot, or a pattern of dots and lines. Just try and make it unique so that you will be able to positively identify it as your ball.
One other thing, consider putting a different mark on your ball that you set aside to use only as your provisional ball. I am sure you might be able to think of a “special” way of marking it.
What happens if you choose to not put an identification mark on your ball?
That is your choice. However, should you hit your ball into an area with another ball of the same brand and number and neither are distinguishable from the other, both balls are lost (Decision 27/10).
For all of the ways in the Rules of Golf there are to get a penalty, I believe a permanent marker is cheap insurance against one.
Believe me; you only need to hit a wrong ball once to decide that you need to put an identifying mark on your ball.
Remember, use the index or the table of contents to find the correct Rule that applies to the situation and follow the Rules of Golf to help yourself to enjoy the game of golf.