The monarchy of Sweden is the constitutional monarchy of the Kingdom of Sweden. The present monarch, Carl XVI Gustaf, has reigned since 15 September 1973. He and his immediate family undertake various official, ceremonial and representational duties. As Sweden is a representative democracy based on a parliamentary system, the monarch has a largely ceremonial role, though officially he or she is head of state and holds the highest public office in Sweden and the highest military and social rank. The Act of Succession of 1810 designates the House of Bernadotte as the Swedish royal house; it also states that the king (and thus implicitly any queen regnant) must be a Protestant Christian (Church of Sweden).