• If the ball, which has crossed the plain-of-touch, touches a player beyond the touch-line, the ball is in-touch, regardless of whether the player is on the ground or jumping in the air. The ball has been put in-touch by the kicking team.

• If a player has one foot in the field-of-play and one foot in-touch, and catches the ball, the team that kicked the ball has put the ball in-touch. The non kicking team has the throw-in to the line-out.

• The only situation where play continues after the ball contacts a player beyond the touch-line is where the ball has not crossed the plane-of-touch and the player plays the ball but does not catch it.
  (Law 19 definition, last paragraph)