what is sealing off in rugby

In rugby, "sealing off" refers to securing oneself to the tackled player, preventing the opposition from grabbing the ball and, if driven back, taking the tackled player and ball with you. It is not allowed for players to seal off the ruck, and they must hold their own body weight and not go off their feet. Sealing off by teammates, not rolling away by the ball carrier, or holding on by the ball carrier if they take the ball with them as they move away from the ruck are all considered illegal. According to Law 15 of World Rugby, players entering the ruck must be on their feet and join from behind their offside line.