A hat is a head covering which is worn for various reasons, including protection against the elements, ceremonial reasons, religious reasons, safety, or as a fashion accessory. In the past, hats were an indicator of social status. In the military, hats may denote nationality, branch of service, rank and/or regiment. Police typically wear distinctive hats such as peaked caps or brimmed hats, such as those worn by the Royal Canadian Mounted Police. Some hats have a protective function. As examples, the hard hat protects construction workers' heads from injury by falling objects and a British police Custodian helmet protects the officer's head, a sun hat shades the face and shoulders from the sun, a cowboy hat protects against sun and rain and a Ushanka fur hat with fold-down ear-flaps keeps the head and ears warm. Some hats are worn for ceremonial purposes, such as the mortarboard, which is worn (or carried) during university graduation ceremonies. Some hats are worn by members of a certain profession, such as the Toque worn by chefs. Some hats have a religious functions, such as the Mitres worn by Bishops and the turban worn by Sikhs.