Icing in hockey is an infraction and is called when a player hits, shoots, or deflects the puck from his team’s half before the center red line to the opponent’s goal line without touching the puck by the players on the other side . Icing is not permitted when the teams are on the power play or at equal strength.
The rule's main purpose is preventing a defending team from delaying the game by, relatively easily, shooting the puck down the ice from their own end.
Here's an example: If a player from Team A shoots the puck from behind their own blue line and it crosses Team B's goal line without being touched by any player from Team B, icing will be called.
