The Commonwealth of Australia has a hybrid form of government. It combines parliamentary government, derived from British political institutions, with a federal system, modelled largely on that of the United States of America. When drafting the Constitution in the 1890's the Founding Fathers wished to adopt the form of government that was most familiar to them. This was the British (or Westminster) parliamentary system that was already being used in each of the six Australian colonies. However, the parliamentary model required significant modifications to accommodate a federal system.
Parliament is both a representative and a law-making body. It comprises representatives of the people who are elected at periodic popular elections, and it is vested with the power to enact laws. Following the British system, the Government or Cabinet - the Prime Minister and Ministers - are drawn from the Parliament. The political party, or coalition of parties, that wins a majority of seats in the lower house of the parliament forms the government.
The British parliamentary system could not be adopted fully as the six states had obtained self government. Britain had a unitary form of government (it no longer has a unitary form of government); a single government has sovereignty over the whole country. However, in the new federal system, the states with their own governmental structure, were to remain largely intact. The Australian parliament was to have only limited sovereignty with limited powers. These powers were those which in the 1890's were seen to be appropriate to a national government, such as defence, communication, currency and coinage. The states were left with a vast range of legislative powers over such areas as agriculture, police, criminal law, price control, road traffic regulations, prisons, power and water supply, education and health.
Another modification to the 'Westminster model' to accommodate the federal system was the establishment of the Senate, an elected house, in which each state, whatever its population, had equal representation. The smaller states, fearing that they could be overwhelmed in the Lower House by the representatives of the more populous states, believed that the Senate would provide some protection of their interests.
A constitutional monarchy is a form of government in which the monarch is the head of state, but legislation is made and administered by an elected government representing the people; the government is typically lead by a Chief or Prime Minister. Often a written Constitution sets out the powers and responsibilities of the head of state and the different levels of government within that system (eg. Australia).
A dictatorship is a form of government in which absolute power is held by one individual. Power is usually obtained and maintained by military might.
A monarchy is a system of government in which the head of state (ie. a king or queen) has absolute power and is appointed in accordance with a line of hereditary or Divine right. The head of state is not elected by the people.
A form of government in which power is vested in a ruling elite, or dominant class. Those in power are not elected by the people.
A republic is a form of Government in which the head of state is elected by the people and is directly responsible to them (eg. The United States of America).