The National Rugby League (NRL) is the top league of professional rugby league football clubs in Australasia. The NRL's main competition, called the Telstra Premiership (due to sponsorship from Telstra Corporation), is contested by sixteen teams, fifteen of which are based in Australia with one based in New Zealand. It is regarded as the world's elite rugby league championship and, per season, is the single most viewed and attended rugby football competition in the world.