A video referee, also known as the instant replay official, television match official or third umpire, is a sports official called upon to help adjudicate a sports match using television footage. Video referees are used in many sports, including cricket, rugby union, rugby league and ice hockey. The role of the video referee differs varies, often they can only be called upon to adjudicate on specific events. Due to the cost of television cameras and other equipment needed for a video referee to function, most sports only employ them at a professional or top-class level.