Prime Minister of Australia
The Prime Minister of the Commonwealth of Australia is the head of government in Australia. The individual who holds the office is the most senior Minister of the Crown, the leader of the Cabinet and the chairperson of the National Security Committee. The office is not mentioned in the Constitution of Australia and exists only through an unwritten political convention and tradition. Despite this, in practice it is the most powerful political position in Australia. The individual who holds the office is commissioned by the Governor-General of Australia.
Almost always and according to convention, the Prime Minister is the leader of the majority party or largest party in a coalition of parties in the House of Representatives. However, there is no constitutional requirement that the prime minister sit in the House of Representatives, or even be a member of parliament, though by convention this is always the case. The only case where a member of the Senate was appointed prime minister was John Gorton, who subsequently resigned his Senate position and was elected as a member of the House of Representatives (Senator George Pearce was acting prime minister for seven months in 1916 while Billy Hughes was overseas).