What is a representative democracy?

Australia is a Representative Democracy with three levels of government, Federal, state and local. What this means is that at each level we vote for an individual to make decisions on our behalf, and each level of government has different roles and responsibilities on behalf of the Australian people.
More information can be found at these sites, as well as others:

What is the federal government responsible for?

The Federal or Commonwealth Government is responsible for the conduct of national affairs. It's areas of responsibility are explicitly stated in the Australian Constitution.
This is the link to the Australian Constitution:

The Federal government can also influence areas outside of its defined role via the provision of public funding for specific purposes, or at the state's request.
It also has influence via their responsibility regarding international treaties.

To summarise Chapter 1 Part V Paragraph 51:

The Parliament shall, subject to this Constitution, have power to make laws for the peace, order, and good government of the Commonwealth with respect to:—

  • Trade with other countries and between the states
  • Customs and excise
  • National debt
  • Communication services
  • Military
  • Federal police
  • Federal courts
  • Navigational aids of waterways
  • Space and weather observations
  • Australian waters – offshore fishing
  • Census and statistics
  • Legal tender
  • Insurance
  • Weight sand measurements
  • Cheques
  • Bankruptcy
  • Copyrights
  • Immigration and emigration
  • International corporations
  • Marriage, divorce and child custody
  • Pensions and support payments
  • Pharmaceutical, medical and dental
  • The judicial system
  • To recognize the laws of the states
  • External affairs and international relations
  • Just acquisition of property for purposes covered by these powers
  • Control of railways for military transport
  • Industrial disputes that cross state lines