The people who assist the refree are called the line judges and they stand on the corner of the court on the opposite side of the server to see something that the head refree may have missed
The 'refree' is an umpire and there can be either
an assist in volleyball is when a setter sets the ball to the hitter for a kill
The refree at the football field gave the defence a penalty.
The Term "Assist" in volleyball is when someone hits the ball into the net on your side of the court and a different team mate hits the ball after it falls out of the net. Generally the hit is directed to the opposite side of the net.
referee
The linesmen are officials in Volleyball games. They stay on the edge on the court and assist the 1st referee on in/out calls.
Umpire
Yes
Football has a referee.
you simply cant
10000 a game
On the side lines