Icing is a rule in hockey designed to prevent a team from dumping the puck deep into its opponent's zone in order to use up the clock or to avoid playing defense. A team is guilty of icing when a player on his own side of the red line dumps the puck all the way past the opponent's goal line without the puck going into the net. In the National Hockey League (NHL), icing is not called until the puck crosses the goal line and an opposing player other than the goaltender touches the puck with his stick. In international play and in most European leagues, there is what's called "no-touch" icing, in which icing is called and play is stopped as soon as the puck crosses the goal line, regardless of whether an opponent touches it.

There are instances in which icing can be "waved off." This is most common when a team is shorthanded. If the opposing team is on a power play, the shorthanded team is allowed to dump the puck at any time from any point on the ice without icing being called. Also, during even-strength play, icing can be waved off if the referee determines that an opposing player could have touched the puck before it crossed the goal line or that the icing was the result of a pass that was missed but could have been reasonably completed. When icing is committed, play stops and a faceoff is held in the defensive zone of the team that iced the puck.

The icing rule is generally successful in preventing teams from running down the clock by dumping the puck, but the NHL felt that a team stuck in its own defensive end for a long period of time would often ice the puck just to be able to make a line change and get fresh players on the ice. In 2005, the NHL modified the icing rule to state that the five players on the ice for the offending team must remain on the ice for the subsequent faceoff. This modification helped to reduce the number of icing penalties by making the penalty for icing stiffer. It also helped to speed up the game by reducing icing calls and reducing the line changes made between an icing call and the subsequent faceoff.