There are over 40 different arm signals that can be used by the referee. Here are the main ones:
The referee raises his arm above his head and points to the spot where the ball has been grounded while standing with his back to the dead ball line.
The referee will clearly raise his arm in the air, pointing towards the side who have been given the penalty.
The referee will raise his arm, bending it square at the elbow. The arm will be pointing towards the team who have been given the free-kick.
The referee will cross both his arms across his chest, like a pair of open scissors.
The referee will move his hands in front of his body. Then he will pretend to pass an imaginary ball forwards.
The referee will raise his arm at head level, with the palm of the hand open, tapping his palm with the other.
The referee will raise his arm across his neck, with the palm of the hand open.
Killing the ball
The referee will point his arm downwards and move it up and down.
Not releasing the ball
The referee will bring both arms close into his chest as if he’s holding an imaginary ball.
Hands in the ruck
The referee will bend forwards and lower his arm towards the ground and then move his arm back and forwards, as if he has handled an imaginary ball on the ground.
The referee will raise one hand above his head with his shoulders in line with touch. He will then move that arm backwards and forwards.
The referee will raise one leg, bending it at the knee. He will then move it up and down, pretending to stamp on an imaginary ball.
The referee will cross his arms above his head to indicate a player has a bleeding injury and may be temporarily replaced.
The referee will have his arm outstretched, waist high, towards the non-offending team, for a period of approximately five seconds.
Award of a scrum
With his shoulders parallel to the with touch-line the referee will have his arm held horizontally pointing towards team to put in the ball.