A referee is an official who watches a whole game of sports and makes all the decisions. The players of the sport being watched must always admit that the referee is always right, even if they aren't. Usually, if any player argues, they can get a yellow card or even sent off with a red card. Referees use a whistle so players and fans can hear when play needs to be stopped. Sometimes referees may have Assistant referees to help them just in case they didn't see something or for offsides in Football (soccer).