A referee is the person who can decide what the result of a game is if the players cannot agree.
Most times this role is played by the tournament director or one of his assistants But in major games the referee is only involved with one game.
From a referee you can expect in depth knowledge of the rules
There are many famous referee descisions and many times they are contested. especially if there is misunderstanding about the rules of the game.
It is interesting to know if under tournament rules? the referee is passive (only act if asked) or active (can also act without being asked)
Under other rules referee's can also decide the outcome. An example in cgos the referee program does decide if its superko rule is broken. without any player having to claim it. maybe this is because it is a computer go tournament and the go text protocol has no standard claim routines.
willemien just found this page missing. Maybe go-players don't like referee's