A referee is an official, in a variety of sports and competition, responsible for enforcing the rules of the sport, including sportsmanship decisions such as ejection. The official tasked with this job may be known by a variety of other titles depending on the sport, including umpire, judge, arbiter (chess), commissaire, or technical official. Referees may be assisted by umpires, linesmen, timekeepers, touch judges, or video review officials.

An official is someone who holds an office in an organization or government and participates in the exercise of authority. An elected official is a person who is an official by virtue of an election. Officials may also be appointed ex officio. Some official positions may be inherited. A person who currently holds an office is referred to as an incumbent. Something "official" refers to something endowed with governmental or other authoritative recognition or mandate, as in official language, official gazette, or official scorer.