If you are going to Australia for travel, then you will be applying the ETA (Subclass 601) visa online. This visa allows you to enter Australia as many times as you want within 12-month period. However, be ware of your passport expiry date. If your passport expiry date is within 12-month, your visa will be granted for less than 12-month. You can stay in Australia for a maximum of 3 months on each trip/visit. The visa fee is AUD20, and the general approval time is around 1-2 days.
Go to http://www.border.gov.au/Trav/Visa-1/601- and click Apply Now.
It will bring you to the page https://www.eta.immi.gov.au/ETAS3/etas and you can click Apply for an ETA to start the application.
You will need to fill in your personal information such as your name, date of birth, passport details, contact, and offshore address.
After filling in the information, it will ask you to pay the visa fee online, and wait its approval.
And then, you are done! Ready to go to Ausss!