Several terms are in use to describe the region comprising Australia and the nations of the Pacific Ocean. The term Oceania is usually preferred, and this is the term in use by the United Nations. The term Pacific Islands generally excludes the islands of New Zealand, and the continent of Australia. The indigenous Māori of New Zealand are Polynesian people.

Historically, the region was called Australasia. This term is based more on natural history (geology, living things, geography) than on politics. This means Australia, New Zealand and the whole of New Guinea, plus those islands which are geologically connected.

The countries (14 total) are listed below according to their UN classification:

Australasia is not a politically designated region. It is a natural region of islands designated by its geologygeographybotany and zoology. It is also an ecozone.