Laws of Rugby - Law 7 - Mode of Play

A match is started by a kick off.
After the kick off, any player who is onside may take the ball and run with it.
Any player may throw it or kick it.
Any player may give the ball to another player.
Any player may tackle, hold or push an opponent holding the ball.
Any player may fall on the ball.
Any player may take part in a scrum, ruck, maul or lineout.
Any player may ground the ball in in-goal.
Whatever a player does must be in accordance with the laws of the game.