To cover up or immobilize the puck to force a stoppage in play. Freezing the puck is most often done by goaltenders when they make a save to make sure they do not give up a rebound or to relieve their team of pressure that their opponents are putting on them.
When goaltenders freeze the puck, the faceoff resulting from the stoppage in play takes place in one of the faceoff circles in their own zone, putting their team at a disadvantage. Because of this, goaltenders must be wise in choosing to freeze the puck or not when they are not under pressure to do so. A situation where a goaltender is more likely to freeze the puck is when his team is shorthanded. His teammates are usually under a lot of pressure to kill off a penalty so the goaltender will freeze the puck to allow a stoppage a play so that his team can get fresh players onto the ice.
Players (forwards or defencemen) can also freeze the puck when they are part of a scramble and opponents are looking to get possession of the puck. Players usually freeze the puck when they are playing in their defensive zone along the boards and there are many opponents around them trying to retrieve the puck. The player will then look to immobilize the puck by using his skate or stick to pin it against the boards, and the referee will whistle a stoppage in play. The faceoff resulting from that stoppage in play will take place in the same zone in which the puck was immobilized.