In ice hockey, an official is responsible for enforcing the rules and maintaining order.
On-ice officials are present on the ice during the game, and traditionally wear a shirt with black and white vertical stripes.
The National Hockey League (NHL) currently employs four on-ice officials in each game—two referees and two linespersons (also known as linesmen).
They are responsible for the general supervision of the game, assess penalties, and conduct face-offs at the beginning of each period and after a goal is scored.
NHL officials wear identifying numbers on the back of their jerseys.