Thanks for your question, Justin. In the Australian Parliament, senators are elected using a system of proportional voting, designed to allocate seats to candidates in proportion to votes cast in an election. Proportional voting allows for a wider range of political parties and/or independents to be elected to the Senate, increasing the range of community viewpoints represented in the Parliament.
To win a seat, a senator must win a quota of first and later preferences. For a state senator at a half-Senate election, this equals 14.3% of the total state vote, while a territory senator must win 33.3% of the total territory vote. The counting procedure for a Senate election is more complicated than the system used for the House of Representatives—it sometimes takes several weeks after an election to count all the Senate votes and finalise the result.
Check out the Australian Electoral Commission’s website for further information about proportional representation.