Hi Alex, thanks for your question.
The way people vote in Australia has changed a lot over time. The first federal election in 1902 used ‘first-past-the-post’ voting for both the Senate and the House of Representatives. Preferential voting was introduced for both the Senate and House in 1918, and is still used to elect members of the House of Representatives.
Preferential voting results in the election of candidates supported by the majority –more than half – of voters. This is because candidates must get over 50% of the vote. In first-past-the-post voting, candidates only need to get the most votes.
Proportional representation was introduced for Senate elections in 1948. In part, this was a response to the lopsided results of previous elections. For example, after the 1946 election there were 3 opposition senators, 33 government senators and no minor party or independent senators. Proportional voting has given minor parties and independent senators representation they wouldn’t have otherwise.