Australasia is a geographical region that generally includes:
- Australia (including its external territories like Christmas Island, Cocos (Keeling) Islands, and Norfolk Island)
- New Zealand
- New Guinea (which includes Papua New Guinea and the Indonesian provinces of Papua and West Papua)
- Neighboring islands in the Pacific Ocean, primarily those in Melanesia (such as Fiji, Solomon Islands, Vanuatu, New Caledonia, and sometimes others like Tonga and Samoa).

It’s important to note that the exact definition of Australasia can vary slightly depending on the context (geopolitical, physiogeographical, ecological, etc.). Sometimes, the term is used more broadly to encompass all of Oceania, or more narrowly to refer only to Australia and New Zealand.
Historically, the term was coined from Latin meaning “south of Asia” and has been used to differentiate the area from Polynesia and the southeast Pacific