An ETA (Electronic Travel Authority) online electronic visa is for people who want to come to Australia for a holiday or business trip up 3 months.
An ETA is equivalent to a visa, but there is no stamp or label in your passport and there is no need for you to visit an Australian diplomatic office to submit an application. You can submit applications directly through this web site and your ETA Visa will generally be approved within 24 hours.
When an application for an ETA is submitted through this site, all you need to do is enter the details from your passport and your credit card or PayPal information. Approved applications are electronically recorded on Australian Government systems.
When you arrive at an airport for check-in on a flight to Australia, the airline check-in staff can electronically confirm that you have authority to board the flight to Australia.