"With these kicks the player tries to kick the ball as far as possible towards the opponents goal and they usually aim for one of the touch lines. If the ball crosses the touch line before being touched by anyone a lineout is awarded to the opposing team. If the ball is put inside the players 22 metre line by a member of the opposition they can kick the ball out on the full and gain ground. Otherwise ground is only gained if the ball bounces in the field of play before crossing the touch line. Care has to be taken not to kick it too far, because if it travels through their opponents in-goal and becomes dead the opposition is awarded a scrum from where the kick occurred. The disadvantage of "kicking for territory" is that it almost always gives possession of the ball back to your opponents. If a clearing kick is successfully caught by the opposition, then they can counter-attack by running, passing, or kicking the ball back toward the clearing team."
from the rugby union wikipedia page