The linesmen primarily look for offside and icing infractions. The referee, on the other hand, is the real policeman on the ice. Only he can call more serious infractions and banish a player to the penalty box. Hockey is a physical game, which has helped its appeal grow worldwide. The stick can also be used legally to try to knock the puck free.
Penalties occur when players do more than check an opponent.
When a penalty is called, the guilty player must sit for two minutes in the penalty box, forcing his team to play short-handed. The penalized player can return to the ice after two minutes or if the opposing team scores a goal. Occasionally, tempers will flare in a physical sport. Although fighting is not encouraged, officials will sometimes let players go at it to let off steam. In these situations, players will receive five minute penalties.