The Constitution is the legal framework for how Australia is governed.
Before 1901 Australia did not exist as a nation. It was a collection of six British colonies which were partly self-governing but under the power of the British Parliament.
The Australian Constitution was drafted at a series of Constitutional Conventions held in the 1890s. It was passed by the British Parliament as part of the Commonwealth of Australia Constitution Act 1900 and took effect on 1 January 1901. This united the colonies as a nation and provided for national government.
Any proposal to change the constitution must first be approved as a bill by the Federal Parliament then voted on in a referendum. If a majority of people in a majority of states and a majority of people across the nation as a whole vote 'yes' (called a double majority), then the proposal to amend the Constitution is agreed to. Otherwise the Constitution remains unchanged.
Prior to 1967 the government had tried to change the constitution at 23 referenda of which only 4 had been approved by enough voters to become law. Those approved include the first referendum in 1906 enabling elections for both Houses of the Parliament to be held concurrently and another in 1946 giving the Commonwealth power to legislate on a wide range of social services.