What visa you are eligible to obtain depends upon what country you hail from. Most backpackers will be on either a Working Holiday or Short-term Visitor Visa (for 3 or 6 months which can be extended in some circumstances)
Australian Working Holiday Visa visa requirements stipulate that this visa is only available to passport holders, without dependent children and between 18 and 30 (incl.), from the United Kingdom, Ireland, Korea, Malta, Canada, the Netherlands, Japan, Germany, Denmark, Sweden, Norway, Hong Kong (SAR), Finland and Cyprus. We have been made aware that the Department of Immigration and Citizenship will make the Working Holiday Visa to US passport holders from 31st October 2007.
Australian Short-term Visitor visas are available from the nearest Australian consulate or embassy in your country. You may be able to apply for an
ETA (Electronic Travel Authority), which means you do not have to submit formal documents, if you are from an ETA-eligible country and you only intend on staying in
Australia for up to 3 months (check the DIAC website for further information).