Most students get into uni with a CSP (Commonwealth-supported place). This means that the federal government pays for most of your education, and you make what's called a 'contribution' through HECS (Higher Education Contribution Scheme). How much the contribution is depends on the course - law, med, dentistry, commerce are most expensive, science is middling and arts, education, nursing are relatively cheap.
You have the choice of paying some or all of your contribution upfront or deferring it to HELP (Higher Education Loans Program). Most people defer their contribution because they can't afford to pay upfront. However, if you pay more than $500 upfront, you get a 25% discount.
If you defer some or all of your contribution to HELP, you'll pay it back through the tax system once you start earning above a certain salary. The tax office will keep track of your HELP debt (you have to give them your tax file number when you enrol at uni), and once you start earning above the threshold they take out a certain percentage each year, until your debt is reduced to zero. Your debt is indexed to inflation, but there's no interest charged.
