An ETA is an electronically stored authority for travel to Australia, and is accessible by Australian border agencies, airlines and travel agents. It's required that you obtain an ETA if you intend to travel to Australia. All non-citizens require a Visa or Electronic Travel Authority to enter Australia.
The great advantage of an ETA is that it is 100% electronic, which allows you to visit Australia without the need to apply through a departmental office for the traditional paper visa.
You can enter Australia as many times as you want for the duration of 12 months from the date your ETA is granted, or until the expiry date of your passport, whichever is earlier.
You can apply for an electronic Australian ETA visa online, if:
Only citizens from the following countries are eligible to apply for an online ETA.
If you do not hold a passport from one of the eligible countries, you have to contact the Australian Mission related to the Visa department and apply for a Visitor Visa (subclass 600).
To apply for an ETA, you must have your passport, email address and a credit card to complete the online application.
The details you provide in your online ETA application need to be exactly the same as they appear in your passport and you must use the same passport that is linked to your online ETA application when you travel.
To apply for ETA you must fill the ETA Application form, Apply for ETA