Australia isnt part of asia , Australia is its own continent , but 1 country rules the continental main land(the country australia) , other countries on the continent are ,papua new guinea , and some pacific ocean nations. also part of indonesia.
Our region is Oceania , but due to the lack of countries in this region we also look at asia.
an example of this is the australian football team who play in the asian confederation.
New zealand is not part of the australian continent because it has its own tectonic plate and not attached to the mainland.