Rucking

A ruck happens after a tackle and it is where the supporting players from both teams (one from each team) converge over the ball on the ground, binding with each other and attempt to push the opposing players backwards off of the ball.  Once your team pushes the other off of the ball, your scrum half can grab the ball and either set up a play or toss it out to the backs.  When he throws the ball out, the man with the ball runs down field until he gets tackled, the man rolls away, and the rucking starts all over again.