The Yang di-Pertuan Agong, also known as the Supreme Head of the Federation, the Paramount Ruler, or simply the Agong and also unofficially as the King of Malaysia, is the constitutional monarch and head of state of Malaysia. The office was established in 1957, when the Federation of Malaya gained independence from the United Kingdom. The Yang di-Pertuan Agong is elected by the Conference of Rulers, comprising the nine rulers of the Malay states, with the office de facto rotated between them, making Malaysia one of the world's few elective monarchies.