The referee controls the contest.   He moves around the mat keeping an eye on the two players while the contest is underway.   He calls the scores, gives out the penalties, and stops and starts the contest as necessary.

The referee is assisted by two corner judges who sit at diagonally opposite corners, just outside the "danger area".   They indicate when players go out of the area and they can also suggest a different score or decision if they disagree with that made by the referee.   (Corner judges may not be used in smaller competitions.)  

At the side of the mat is the control table.   Here sit the timekeeper(s), who time the length of the competitions and the length of the hold downs, the scorer(s) who put the scores up on the scoreboard, and the recorder(s) who record the results of the contests and make sure that the correct players are fighting each other.   In smaller competitions some of the roles at the control table may be combined.