What type of island is Australia?

In geographical terms, Australia is not considered an island, but a continent.

As a landform, it could be considered an island as it is entirely surrounded by water and not joined onto any other land mass. For this reason, it is often referred to as an island continent. Australia is too big to be formally classified as an island. The world's largest island is Greenland.

Another reason why Australia is also considered a continent is because it sits on its own tectonic plate. This is different from Greenland, which uses the same land mass as North America. That is why the geological appearances are much different in Australia from anywhere else. A place like Greenland shares the same geologic attributes as North America.