The Australian Senate is one of the Houses in the Parliament of Australia along with the Australian House of Representatives. It is very similar to the United States Senate in the sense that it is the upper house and has less members that the House of representatives. Senators are elected using proportional representation and some preferential voting. There are 12 Senators from each of the 6 states in Australia (despite their population differences) and 2 each from the 2 territories making a total of 76 Senators.
Voting on bills
If a bill is introduced into the House of Representatives and is successfully passed it then goes to the Senate where it will be debated and then a vote will be held in relation to that bill. As the Senate uses proportional representation it means that once a quota for 1 Senator is reached then that Senator is elected and because of this even if a party such as the Liberal party is in a minority in the House of Representatives it has the same amount of Senators as the ALP in the Senate at 32 each. This means that the ALP or the Liberal Party after passing the bill in the House of Representatives often find it difficult to pass the bill in the Senate as they need 39 Senators to pass that bill.
As mention before the Senate has 12 Senators from each of the 6 states and 2 from the 2 territories.
NSW: 6 ALP, 4 Liberal, 2 National
VIC: 5 ALP, 6 Liberal, 1 Family First
QLD: 5 ALP, 5 Liberal, 2 National
WA: 4 ALP, 6 Liberal, 2 Green
SA: 5 ALP, 5 Liberal, 1 Green, 1 Ind
TAS: 5 ALP, 5 Liberal, 2 Green
ACT: 1 ALP, 1 Liberal
NT: 1 ALP, 1 Liberal
This gives a total of 32 Senators for the Australian Labor Party, 33 Senators for the Liberal Party, 5 green Senators, 4 National Senators, 1 Family first Senators and 1 Independent.
Re-election and terms
At every federal election their are 40 Senators up for re-election. This is comprised of 6 from each state and 2 from each territory. Senators serve terms of 6 years which is double what House of Representative members serve. A double-dissolution election can be called if there is deadlock in the Senate and the last time this occurred was during the Whitlam era nearly 40 years ago.