In which sport do referees and other officials wear black-and-white vertically striped shirts?

As the name implies, on-ice officials do their job on the hockey rink. They are traditionally clad in a black hockey helmet, black trousers, and a black-and-white vertically striped shirt. They wear standard hockey skates and carry a finger whistle, which they use to stop play. They communicate with players, coaches, off-ice officials, both verbally and via hand signals. Starting in 1955 with the introduction of the black-and-white jersey, NHL on-ice officials wore numbers on their back for identification. In 1977, NHL officials removed the number and had only their surnames on the back of their jerseys for identification, normally in a single row across the shoulders. However, in 1994, NHL officials returned to wearing solely numbers on their shirts, a procedure adopted by other sports leagues.

In the early days of hockey when the NHL was formed (1917), the referees would be clad in a vest and tie along with their pants and carry a bell, not a whistle, to stop the game in progress. In those days, penalties were assessed more on common sense rather than following strict rules, and the official would deem what was allowed and not, as well as the length of the penalties.

Later, NHL referees wore cream-colored sweaters over a shirt and tie, from the 1930s to the early 1950s. They then briefly wore orange sweaters with half-zip fronts (and without neckties), until the black-and-white-striped jersey was introduced in 1955.