You can apply for an eVisitor when you're traveling to Australia for tourism, business or a conference. With an eVisitor you can stay in Australia for up to 90 days per entry. The following nationalities are eligible for an eVisitor:
Andorra, Austria, Belgium, Bulgaria, Czech Republic, Croatia, Cyprus, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Monaco, Netherlands, Norway, Poland, Portugal, Romania, San Marino, Slovenia, Slovakia, Spain, Sweden, Switzerland, Vatican City, United Kingdom.
Is your nationality not mentioned, do you intend to travel to Australia for a reason other than tourism/business/conference or do you want to stay in the country for more than 90 days? Then you need to apply for your visa through the website of the Australian Department of Immigration and Border Protection.