When a ball carrier has been tackled to the ground, they have to let go of the ball.

No excuses - the laws say so, so you've got to release the ball.

But often players purposely hold onto the ball when they have gone down in a tackle.

This is to stop the other team getting hold of the ball and starting a quick attack.

But if the referee sees a player holding onto the ball on the ground, he will immediately award a penalty to the opposing team.