World Rugby is the world governing body for the sport of rugby union. World Rugby, founded in 1886, organises the Rugby World Cup every four years, the sport's most recognised and most profitable competition. It also organises a number of other international rugby competitions, such as the World Rugby Sevens Series, the Rugby World Cup Sevens, the World Under-20 Championship, and the Pacific Nations Cup. World Rugby's headquarters are in Dublin, Ireland. Its membership now comprises 120 national unions.