There are three visas that you can apply for online to visit Australia for tourism or business visitor activities:
Tourism includes holidays, recreation and seeing family and or friends.
Business visitor activities may include attending a conference, negotiation or an exploratory business visit.
Note: If you intend to visit for medical treatment or to transit through Australia, you should not apply for a Visitor visa.
If you intend to visit for medical treatment you will need to apply for Medical Treatment visa (subclass 602).
To transit through Australia you will need to apply for a Transit visa (subclass 771).