This rule is the most unique skill of rugby league that makes it so different from rugby union.
Each team is allowed six tackles.
If they have not scored during their six tackles, the ball goes back to the opposition.
The tackled player must be immediately released by the tackler and cannot be touched again until the ball is back in play.
After the player with the ball is tackled, they must lift the ball clear of the ground, face their opponent's goal line and roll it under their foot to the player behind them, the acting half back.
The ball has to always travel backwards.
A player can play the ball to themselves by heeling it backwards, stepping over the ball and then picking it up to run with it or to pass to another player.
Once they've done this, their team has one less tackle to play with.
For example, if a player is tackled on the second tackle, the referee will then shout "third tackle" on the play of the ball.
The team will have only three more tackles left on the scoreboard.
The BBC is not responsible for the content of external internet sites