The teeing grounds on any given golf course typically include several different sets of tee boxes. This is to give golfers of different skill levels the option to play the course from shorter or longer distances.
The championship tees are those tee markers that are farthest back on each teeing ground. If you play from the championship tees, you are playing the course as its maximum length. And that means that only highly skilled golfers should play from the championship tees. A 30-handicapper who tries to play from the championship tees is only making things much harder for himself and, likely, for others by slowing down play.
The term derives because the back tees are often the ones used in tournament play - club championships, for example. Hence, "championship tees."
