Leinster Rugby (Irish: Rugbaí Laighean) is one of the four professional provincial rugby teams from the island of Ireland and the most successful Irish team both domestically and in European competition. They compete in the Pro12 and the European Rugby Champions Cup. The team represents the Irish Rugby Football Union (IRFU) Leinster Branch, which is one of four primary branches of the IRFU and is responsible for rugby union throughout the geographical Irish province of Leinster.