The Senate is the upper house of the bicameral Parliament of Australia, the lower house being the House of Representatives. The composition and powers of the Senate are established in Chapter I of the Constitution of Australia. There are a total of 76 senators: 12 are elected from each of the six Australian states regardless of population and 2 from each of the two self-governing internal Australian territories. Senators are popularly elected under the single transferable vote system of proportional representation.

Bicameralism is a type of legislature that is divided into two separate assemblies, chambers, or houses, known as a bicameral legislature. Bicameralism is distinguished from unicameralism, in which all members deliberate and vote as a single group. As of 2022, roughly 40% of the world's national legislatures are bicameral, while unicameralism represents 60% nationally and much more at the subnational level.