Elections in Australia take place periodically to elect the legislature of the Commonwealth of Australia, as well as for each Australian state and territory and for local government councils. Elections in all jurisdictions follow similar principles, although there are minor variations between them. The elections for the Australian Parliament are held under the federal electoral system, which is uniform throughout the country, and the elections for state and territory Parliaments are held under the electoral system of each state and territory. Part IV of Chapter 1 of the Australian Constitution briefly deals with eligibility for voting and election to the federal Australian Parliament. It does not prescribe how elections should be conducted. Election campaigns and associated political advertisements are subject to some regulation. Public funding of political parties and party registration was introduced in 1983. Voting for the federal and each state and territory parliament is compulsory for Australian citizens over the age of 18. Voting is almost entirely conducted using paper ballots. The informal vote is not usually significant, but a donkey vote is more common, and may have a deciding impact in marginal seats. Parliaments Voting for the federal and each state and territory parliament is compulsory for Australian citizens over the age of 18. Federal Parliament The Australian Parliament consists of two chambers, the House of Representatives (commonly also referred as the lower house) and the Senate (also referred as the upper house). The House of Representatives has 151 members, elected for a maximum term of three years in single-member constituencies (each approximately equal in voters). Elections are conducted by a system of preferential voting (also called alternative voting or instant-runoff voting). The Senate has 76 senators, elected through a preferential system of proportional representation with a system of single transferable vote, with each state constituting a single constituency normally returning 6 senators every three years and each territory constituting a single constituency returning two senators. Electors in the two territories elect senators for non-fixed terms that are defined by the term of the House of Representatives. State senators normally serve fixed six-year terms, with half of the seats in each State expiring every three years. In the event of a double dissolution, the terms of all the members of the Senate and the House of Representatives seats end immediately. State Parliaments and Territory Legislative Assemblies South Australia The Parliament of South Australia is a bicameral legislature.