What is "icing" in hockey?

In hockey, "icing" is called when a player shoots or deflects the puck from his own side of the center line across the opposing team's goal line. Once icing has been called, the play is ruled dead, and the puck is returned to the shooting team's zone for a face-off.

The icing rule is not in effect when a team is playing short-handed. Penalty-killers try to shoot the puck the length of the ice to burn up penalty time by forcing their opponents to skate back to their own zone for the puck. Icing can also be waived by officials if the defending team allows the puck to cross the goal line even though it appeared to be playable before reaching the line.