Icing in ice hockey is a rule the happens when a player shoots the puck across at least two red lines, the other team's goal line being the last, and the puck remains untouched but it is not icing if the player shoots the puck from behind the halfway line of the ice into the goal. If the goal went into the net it would be counted as a goal. There is also automatic or no-touch icing which is used mostly in lower-level professional hockey leagues like the ECHL and Central Hockey League, It was enforced in 1990 after Luděk Čajka, a Czech player rushed to get to the puck in an icing situation, he crashed into the boards, suffered severe spinal injuries, and died a few weeks later. Sometimes the goaltender will raise his hand for icing also.
If icing is waved off by a referee it is either because: