A State of Origin competition is a type of sporting event between players representing their state or territory. State of Origin began in Australian rules football on 8 October 1977 between Western Australia (WA) and Victoria, at Subiaco Oval in Perth, the initial brainchild of Leon Larkin. The selection criteria for Australian football have varied, but they are generally applied to players who have played most of their juniors games in a particular state or territory, hence the name "State of Origin". In Rugby League the criteria are different, where players are selected for where they either first played senior Rugby League or where they played in the majority of senior competitions. The annual Rugby League State of Origin series is one of Australia's most popular sporting events. The name is also used in Australia for small sporting events which generally involve domestic representative teams.

It was devised to address the drift of most talented Australian rules players to the Victorian Football League (VFL) and the effect that this had on interstate matches. A similar situation existed in regard to the New South Wales Rugby League which attracted the best players from the Queensland Rugby League because of its far stronger and financially attractive competition. The latter was due to the increased funds of the New South Wales clubs, due to poker machines, which Queensland laws prohibited.