A golf ball marker is a device attached to the golf ball to identify it as belonging to a player.
Golf markers come in different shapes and sizes.
There are two main types of markers; the most common ones are the tee-marker and the ball-marker. The tee-marker is usually made of wood or plastic and has two holes drilled into it, one at each end.
This allows the golfer to place it on top of the tee or ground at an angle to see their ball from any direction on the course quickly. The ball-marker is just like a tee-marker but much smaller and lighter, so you can place it on top of a golf ball without damaging it.