When golfers show up to a golf course, either for their regular game or for the first time, they have to pick which set of tees they want to play. Sometimes it's a personal decision. Often times, it's a group decision. No matter which tees people decide to play, though, they pick a set and go with it.
Then you get to the first hole, and you find the set of tees that you picked -- either based on color, or their number, or their symbol. But tee markers on a golf course are not universal and don't look the same, and that's sometimes true even on the same course.
Some courses use simple tee markers like a block of wood or a log. Some courses use more ornate tee markers, like the club's logo. Some have plaques in the ground that indicate where to start the hole.
What can be used as a tee marker on the golf course?
As it turns out, there's basically no restriction on what can be used as a tee marker on the golf course. Under the Rules of Golf, the teeing area is explained as the space where "the front edge is defined by the line between the forward-most points of two tee-markers set by the Committee, and the side edges are defined by the lines back from the outside points of the tee-markers."
Nowhere in the rules does it say the tee markers have to have a certain appearance or size. They don't even have to match, actually. So long as golfers can discern what constitute the tee markers, then a golfer can draw the invisible lines of the teeing area from the front and side edges of the markers.
Is there any rule that limits what can be used as a tee marker on the golf course?
Believe it or not, a golf course technically doesn't even need to have actual tee markers. For the purposes of a competition, golfers just need to know the definition of the teeing area. For example, at Baltusrol Golf Club in New Jersey, they have plaques on each hole that indicate the general area of different tees. Golfers then have a sheet they use to indicate where the tee box is relative to that plaque. They don't put out daily tee markers to save mowing and prep time.
Whatever is used to indicate the teeing ground, though, cannot be changed or ignored by individual players in a friendly game or competition. The ball must be played out of the same teeing area for all players, and the markers cannot be moved to make the space wider or narrower.